how to fix a runtime error in python

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Python RuntimeError (Examples & Use Cases) | Initial Commit

Table of Contents

Introduction, what is a runtimeerror error, what causes run time error message in python, how do you handle a runtime error, what is runtime error message example, zero division error raised, index error, how do i fix a built-in exception value error in python, what causes the built-in exception overflow error.

There are several types of errors in Python that help you debug your program. When you run your program, Python first checks for any syntax errors, and then runs the program. Errors thrown during syntax checking are called syntax errors . Errors that are thrown once the code is run are under the class of runtime errors . These errors will always include an error message printed to the interpreter. In this tutorial, you will learn several different types of runtime errors in python, what their error messages are, and how to fix them.

A python run-time error is a class of python built-in exceptions that are thrown at run-time. There are many different types of run-time errors, we will cover them in this article. Some examples include type errors and name errors. run-time attribute errors fall under a larger group of concrete built-in exceptions in Python.

There are many things that can raise a runtime errors in python depending on the type of error that is thrown. Some questions you can ask yourself to debug including, are you:

• dividing by zero?
• using incorrect types in operations?
• indexing past the length of a list?
• accessing a key in dictionary that doesn't exist?
• using variables that haven't been defined yet?
• trying to import or access a file that does not exist?

If you checked for all of these things and you are still getting an error, then it may be caused by something else. We will cover some examples of causes and fixes of certain errors in the following sections.

How you handle a run-time error in python depends on the specific error that was thrown. Once way to generally handle run-time errors is by using a try/except block. You include the code that may cause a runtime error in the try clause. You can then specify how you want to handle the code in the case of an error in the except clause. Here is an example:

This way you are alerted of the error without causing a raised exception and stopping your program.

Every run-time error in python prints a message to the interpreter indicating what caused raised error and what line it was on. Let's take a look at some examples of common run-time errors and how to fix them.

A ZeroDivisionError is thrown when you try to divide or modulo by zero in your code, for example:

Note that the error message idicates the error is happening on line 3. We can avoid this by adding a check to make sure the number we're modding by isn't 0 before we perform the operation:

A TypeError is thrown when you try to perform an operation with incorrect types. For example, if you tried to concatenate an int and a string, you get a type error:

The error will also specify which operation is throwing the error and what types you're trying to use. In this case we can resolve this error by casting all the variables to integers to make sure we are only adding integers:

Another common cause for type errors is attempting to loop through an incorrect type. For example, attempting to iterate through an integer:

In this case the error tells us that we are attempting to iterate through an integer on line 3, which is not a type we can iterate through. Instead we want to use a for-range loop:

One example of a library function that can throw a type error is the pandas.head() method from the Pandas library. The head function throws a type error if you provide an argument that is not an integer:

You can learn more about the pandas head function here .

A KeyError is thrown when you are trying to access a key in a dictionary that doesn't exist. For example:

The error will specify which key you are trying to access that does not exist. You can fix this by making sure to check if the key is in the dictionary before trying to access that specific key. You can check if a key exists in a dictionary by using the in function, which returns a boolean:

An index error is caused by indexing into a list with an out of bounds index:

We can fix this by either adjusting the for loop to only loop over the range of the list, or adding a check before we index into the list to make sure the index is in range:

A NameError is thrown when you try to use a variable that is not defined yet in the file. For example:

You can fix this by defining the variable on a line before the line it is called on:

Name errors can also be thrown if you try to use a variable that is already defined but out of scope. For example, if you try to use a local variable defined inside of a function globally:

To fix this, make sure you are only trying to access variables that are within scope.

File not found error

A FileNotFoundError is thrown when you try to access a file that does not exist in the directory you specified:

There are a couple ways to resolve the error. First you should check to make sure that the file you are trying to access is in your current directory. If not, make sure to specify the full filepath when trying to access that file, for example:

A value error is caused by giving a function an input that is of the correct type, but an incorrect value. For example:

Here we get an error because the math.sqrt function only works with positive integers or zero as input. We can prevent this error by making sure that anything passed into the function is greater than or equal to zero.

An overflow error is caused by an arithmetic operation that is too large for Python to represent.

For example:

You can prevent overflow errors by making sure that the numbers you pass into functions are not too large.

In this tutorial, you learned that run-time errors are, when they occur in your program, and several ways to fix them. First, you learned that run-time errors are a type of built-in exceptions thrown at run-time. Next, you learned some common causes of run-time errors like dividing by zero and using incorrect types in operations. Then, you learned how to generally handle run-time errors using a try-except block. Last, you looked at several examples of things that can raise run-time errors and how to resolve them, including some less common errors like overflow errors and value errors.

If you're interested in learning more about the basics of Python, coding, and software development, check out our Coding Essentials Guidebook for Developers , where we cover the essential languages, concepts, and tools that you'll need to become a professional developer.

Thanks and happy coding! We hope you enjoyed this article. If you have any questions or comments, feel free to reach out to [email protected] .

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What Are the Different Types of Python Errors? – and How to Handle Them

Table of Contents

There are several types of errors that can occur in Python. Each type indicates a different kind of problem in the code, and comprehending these error types is crucial in creating effective Python applications.

The most common types of errors you'll encounter in Python are syntax errors, runtime errors, logical errors, name errors, type errors, index errors, and attribute errors. Let's go through each with examples.

How Do I Know What Type of Error I Have?

When Python encounters an error, it typically stops the program and displays an error message that indicates the type of error and the line number where the error occurred.

1. Syntax Errors

A syntax error occurs in Python when the interpreter is unable to parse the code due to the code violating Python language rules, such as inappropriate indentation, erroneous keyword usage, or incorrect operator use. Syntax errors prohibit the code from running, and the interpreter displays an error message that specifies the problem and where it occurred in the code. Here's an example of a Python syntax error:

When the above code is executed in an IDE, we get the following output message that describes the error and the location in the code where it occurred:

It shows that there is a SyntaxError on line 2 of the file demo.py .

The SyntaxError occurs on line 2 because the if statement is missing a colon : at the end of the line. The correct code should be:

This code will execute correctly and print x is 10 to the console because the SyntaxError has been fixed.

2. Runtime Errors

In Python, a runtime error occurs when the program is executing and encounters an unexpected condition that prevents it from continuing. Runtime errors are also known as exceptions and can occur for various reasons such as division by zero, attempting to access an index that is out of range, or calling a function that does not exist.

Types of runtime errors

Runtime errors can be challenging to debug because they occur at runtime and can be difficult to reproduce. To fix a runtime error, we need to identify the cause of the error and modify the code to handle the error or avoid it altogether. Below are some specific types of runtime errors.

1. NameError:

A NameError in Python is raised when the interpreter encounters a variable or function name that it cannot find in the current scope. This can happen for a variety of reasons, such as misspelling a variable or function name, using a variable or function before it is defined, or referencing a variable or function that is outside the current scope. Here's an example of a NameError in Python:

When the above code is run in an IDE, we get the following output:

This error message indicates that the interpreter could not find the variable w in the current scope. To fix this error, we need to correct the misspelling of the variable name to y , like so:

Now the code will run without any errors, and the output will be 15 , which is the correct result of adding x and y .

2. TypeError:

In Python, a TypeError is raised when an operation or function is applied to an object of an inappropriate type. This can happen when trying to perform arithmetic or logical operations on incompatible data types or when passing arguments of the wrong type to a function. Here's an example of a TypeError in Python:

When the above code is executed in an IDE, we get the following error message:

This error message indicates that we cannot concatenate a string and an integer using the + operator. To fix this error, we need to convert the integer y to a string before concatenating it with x , like so:

Here, we have used the str() method to convert our integer to a string. Now the code will run without any errors, and the output will be 105 , which is the result of concatenating x and y as strings.

3. IndexError

An IndexError is raised in Python when we try to access an index of a sequence (such as a string, list, or tuple ) that is out of range. This can happen when we try to access an element that doesn't exist in the sequence or when we try to access an element at an index that is greater than or equal to the length of the sequence. Here's an example of an IndexError in Python:

This error message indicates that we are trying to access an index that is outside the range of valid indices for the list. To fix this error, we need to make sure that we are only accessing valid indices of the list, like so:

Now the code will run without any errors, and the output will be 500 , which is the element at index 4 of the list.

4. AttributeError

In Python, an AttributeError is raised when you try to access an attribute or method of an object that does not exist or is not defined for that object. This can happen when you misspell the name of an attribute or method or when you try to access an attribute or method that is not defined for the type of object you are working with. Here's an example of an AttributeError in Python:

Output for the above code:

This error message indicates that we are trying to access an attribute (reverse) that is not defined for the type of object (str) we are working with.

To fix this error, we need to use a different method or attribute that is defined for strings, like [::-1] to reverse the string:

Now the code will run without any errors, and the output will be !dlrow ,olleH , which is the reversed string of my_string .

3. Logical Errors

A logical error occurs in Python when the code runs without any syntax or runtime errors but produces incorrect results due to flawed logic in the code. These types of errors are often caused by incorrect assumptions, an incomplete understanding of the problem, or the incorrect use of algorithms or formulas.

Unlike syntax or runtime errors, logical errors can be challenging to detect and fix because the code runs without producing any error messages. The results may seem correct, but the code might produce incorrect output in certain situations. Here is an example of a logical error in Python:

In this example, the function calculate_factorial() is designed to calculate the factorial of a given number n . So when we run it, let's say for n = 5 , it runs without any problem but gives an output of 24 instead of 120 . The reason is a logical error in the code that causes it to produce incorrect results. The for loop is iterating from 1 to n-1 instead of from 1 to n , causing the issue. This means that the factorial is being calculated incorrectly, resulting in an incorrect output.

To fix this logical error, we need to change the range of the for loop to include the number n itself. Here's the corrected code:

Though we have discussed only 7 types of errors that are encountered frequently, the list doesn’t end here. There are many more built-in errors in Python, like KeyError , MemoryError , ImportError , etc.

How to Handle Errors with the Try-Except Block in Python

Error handling in Python is typically done using try-except blocks, which allow us to catch and handle exceptions that might otherwise cause our program to crash or behave unpredictably. An example of a simple try-except block in Python is:

In this example, we are trying to get user input and perform a calculation. However, there are two potential errors that could occur: the user might enter a non-integer value, or they might enter zero as the input. To handle these errors gracefully, we use a try-except block.

The try block contains the code that might raise an exception , such as the int() function call or the division operation. If an exception occurs within the try block , execution immediately jumps to the appropriate except block , based on the type of exception that occurred. In this case, if a ValueError occurs (because the user entered a non-integer value), we print a message indicating that the input was invalid. If a ZeroDivisionError occurs (because the user entered zero), we print a message indicating that the input was invalid. If no exception occurs, the except blocks are skipped, and the code continues to execute normally.

By using try-except blocks and appropriately handling exceptions in your code, you can prevent unexpected errors, improve the reliability of your code, and provide a better experience for your users.

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Python Try and Except Statements – How to Handle Exceptions in Python

When coding in Python, you can often anticipate runtime errors even in a syntactically and logically correct program. These errors can be caused by invalid inputs or some predictable inconsistencies.

In Python, you can use the try and the except blocks to handle most of these errors as exceptions all the more gracefully.

In this tutorial, you'll learn the general syntax of try and except . Then we'll proceed to code simple examples, discuss what can go wrong, and provide corrective measures using try and except blocks.

Syntax of Python Try and Except Blocks

Let's start by understanding the syntax of the try and except statements in Python. The general template is shown below:

Let's look at what the different blocks are used for:

• The try block is the block of statements you'd like to try executing. However, there may be runtime errors due to an exception, and this block may fail to work as intended.
• The except block is triggered when the try block fails due to an exception. It contains a set of statements that often give you some context on what went wrong inside the try block.
• You should always mention the type of error that you intend to catch as exception inside the except block, denoted by the placeholder <error type> in the above snippet.
• You might as well use except without specifying the <error type> . But, this is not a recommended practice as you're not accounting for the different types of errors that can occur.

In trying to execute the code inside the try block, there's also a possibility for multiple errors to occur.

For example, you may be accessing a list using an index that's way out of range, using a wrong dictionary key, and trying to open a file that does not exist - all inside the try block.

In this case, you may run into IndexError , KeyError , and FileNotFoundError . And you have to add as many except blocks as the number of errors that you anticipate, one for each type of error.

• The else block is triggered only if the try block is executed without errors. This can be useful when you'd like to take a follow-up action when the try block succeeds. For example, if you try and open a file successfully, you may want to read its content.
• The finally block is always executed, regardless of what happens in the other blocks. This is useful when you'd like to free up resources after the execution of a particular block of code.

Note : The else and finally blocks are optional. In most cases, you can use only the try block to try doing something, and catch errors as exceptions inside the except block.

Over the next few minutes, you'll use what you've learned thus far to handle exceptions in Python. Let's get started.

How to Handle a ZeroDivisionError in Python

Consider the function divide() shown below. It takes two arguments – num and div – and returns the quotient of the division operation num/div .

▶ Calling the function with different numbers returns results as expected:

This code works fine until you try dividing by zero:

You see that the program crashes throwing a ZeroDivisionError :

You can handle this division by zero as an exception by doing the following:

• In the try block, place a call to the divide() function. In essence, you're trying to divide num by div .
• Handle the case when div is 0 as an exception inside the except block.
• In this example, you can except ZeroDivisionError by printing a message informing the user that they tried dividing by zero.

This is shown in the code snippet below:

With a valid input, the code still works fine.

When you try diving by zero, you're notified of the exception that occurs, and the program ends gracefully.

How to Handle a TypeError in Python

In this section, you'll see how you can use try and except to handle a TypeError in Python.

▶ Consider the following function add_10() that takes in a number as the argument, adds 10 to it, and returns the result of this addition.

You can call the function add_10() with any number and it'll work fine, as shown below:

Now try calling add_10() with "five" instead of 5 .

You'll notice that your program crashes with the following error message:

The error message TypeError: can only concatenate str (not "int") to str explains that you can only concatenate two strings, and not add an integer to a string.

Now, you have the following:

• Given a number my_num , try calling the function add_10() with my_num as the argument. If the argument is of valid type, there's no exception
• Otherwise, the except block corresponding to the TypeError is triggered, notifying the user that the argument is of invalid type.

This is explained below:

Since you've now handled TypeError as an exception, you're only informed that the argument is of invalid type.

How to Handle an IndexError in Python

If you've worked with Python lists, or any Python iterable before, you'll have probably run into IndexError .

This is because it's often difficult to keep track of all changes to iterables. And you may be trying to access an item at an index that's not valid.

▶ In this example, the list my_list has 4 items. The valid indices are 0, 1, 2, and 3, and -1, -2, -3, -4 if you use negative indexing.

As 2 is a valid index, you see that the item at index 2 , which is C++ , is printed out:

If you try accessing an item at index that's outside the range of valid indices, you'll run into an IndexError :

If you're familiar with the pattern, you'll now use try and except to handle index errors.

▶ In the code snippet below, you try accessing the item at the index specified by search_idx .

Here, the search_idx ( 3 ) is a valid index, and the item at the particular index is printed out:

If the search_idx is outside the valid range for indices, the except block catches the IndexError as an exception, and there are no more long error messages. 🙂

Rather, the message that the search_idx is out of the valid range of indices is displayed:

How to Handle a KeyError in Python

You have likely run into KeyError when working with Python dictionaries

▶ Consider this example where you have a dictionary my_dict .

• The dictionary my_dict has 3 key-value pairs, "key1:value1" , "key2:value2" , and "key3:value3"
• Now, you try to tap into the dictionary and access the value corresponding to the key "non-existent key" .

As expected, you'll get a KeyError :

You can handle KeyError in almost the same way you handled IndexError .

• You can try accessing the value corresponding to the key specified by the search_key .
• If search_key is indeed a valid key, the corresponding value is printed out.
• If you run into an exception because of a non-existent key, you use the except block to let the user know.

This is explained in the code snippet below:

▶ If you want to provide additional context such as the name of the invalid key, you can do that too. It's possible that the key was misspelled which made it invalid. In this case, letting the user know the key used will probably help them fix the typo.

You can do this by catching the invalid key as <error_msg> and use it in the message printed when the exception occurs:

▶ Notice how the name of the key is also printed out:

How to Handle a FileNotFoundError in Python

Another common error that occurs when working with files in Python is the FileNotFoundError .

▶ In the following example, you're trying to open the file my_file.txt by specifying its path to the function open() . And you'd like to read the file and print out the contents of the file.

However, you haven't yet created the file in the specified location.

If you try running the code snippet below, you'll get a FileNotFoundError :

And using try and except , you can do the following:

• Try opening the file in the try block.
• Handle FileNotFoundError in the except block by letting the user know that they tried to open a file that doesn't exist.
• If the try block succeeds, and the file does exist, read and print out the contents of the file.
• In the finally block, close the file so that there's no wastage of resources. Recall how the file will be closed regardless of what happens in the file opening and reading steps.

Notice how you've handled the error as an exception and the program ends gracefully displaying the message below:

▶ Let's consider the case in which the else block is triggered. The file my_file.txt is now present at the path mentioned earlier.

And here's what the file my_file.txt contains:

Now, re-running the earlier code snippet works as expected.

This time, the file my_file.txt is present, the else block is triggered and its contents are printed out, as shown below:

I hope this clarifies how you can handle exceptions when working with files.

In this tutorial, you've learned how you can use try and except statements in Python to handle exceptions.

You coded examples to understand what types of exception may occur and how you can use except to catch the most common errors.

Hope you enjoyed this tutorial. Happy coding! Until next time :)

I am a developer and technical writer from India. I write tutorials on all things programming and machine learning.

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Fixing Runtime Errors in Python: A Comprehensive Guide

Abstract: Learn how to troubleshoot and fix runtime errors in your Python code. Follow this step-by-step guide to become a more efficient Python developer.

Python is a popular and widely used programming language, known for its simplicity and readability. However, even experienced Python developers may encounter runtime errors, which can be frustrating and difficult to debug. In this article, we will provide a comprehensive guide to fixing runtime errors in Python, covering key concepts, applications, and significance.

What are Runtime Errors?

Runtime errors, also known as execution-time errors, are errors that occur while a program is running. These errors can be caused by a variety of factors, such as logical mistakes, syntax errors, or incorrect data types. Unlike syntax errors, which are caught by the interpreter before the program is executed, runtime errors occur during program execution and can be more difficult to diagnose and fix.

Common Runtime Errors in Python

Some of the most common runtime errors in Python include:

• TypeError : Raised when an operation or function is applied to an object of inappropriate type.
• ValueError : Raised when an operation or function receives an argument of correct type but inappropriate value.
• NameError : Raised when a variable is not defined.
• ZeroDivisionError : Raised when the second argument of a division or modulo operation is zero.

Debugging Runtime Errors in Python

Debugging runtime errors in Python can be challenging, but there are several techniques that can help. Here are some tips:

• Use print statements to check the values of variables and expressions.
• Use a debugger to step through the code and inspect variables and data structures.
• Use logging to record information about the program's execution and any errors that occur.
• Use exception handling to catch and handle runtime errors gracefully.

Example: Finding the Longest Common Prefix

Let's consider an example problem: finding the longest common prefix of a list of strings. Here's a possible solution:

In this example, we first check if the input list is empty. If so, we return an empty string. Otherwise, we initialize an empty string res to store the longest common prefix. We then iterate over the characters of the first string in the list, checking if each character is present in all the other strings. If a character is not present in all the other strings, we return the current value of res . Otherwise, we append the character to res .

Significance of Fixing Runtime Errors

Fixing runtime errors is essential for writing reliable and robust software. By addressing runtime errors, developers can improve the stability and performance of their code, reduce the risk of data corruption or loss, and enhance the user experience.

• Python Tutorial: Errors and Exceptions
• Debugging in Python: Using pdb to Step Through Code
• Python Logging Module
• Find Longest Common Prefix in a String Array

This article has provided a comprehensive guide to fixing runtime errors in Python, covering key concepts, applications, and significance. By understanding the common types of runtime errors and using effective debugging techniques, developers can improve the reliability and robustness of their code.

(Note: The code block above is just a snippet, the complete code should be enclosed within tags)

(Summary: This article provides a comprehensive guide to fixing runtime errors in Python, covering key concepts, applications, and significance. It includes examples and techniques for debugging runtime errors, as well as references to further resources.)

Tags: :  Python Debugging Software Development

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3.6. Runtime Errors ¶

The second type of error is a runtime error . A program with a runtime error is one that passed the interpreter’s syntax checks, and started to execute. However, during the execution of one of the statements in the program, an error occurred that caused the interpreter to stop executing the program and display an error message. Runtime errors are also called exceptions because they usually indicate that something exceptional (and bad) has happened.

Here are some examples of common runtime errors you are sure to encounter:

Misspelled or incorrectly capitalized variable and function names

Attempts to perform operations (such as math operations) on data of the wrong type (ex. attempting to subtract two variables that hold string values)

Dividing by zero

Attempts to use a type conversion function such as int on a value that can’t be converted to an int

The following program contains various runtime errors. Can you spot any of them? After locating the error, run the program to see the error message.

Notice the following important differences between syntax errors and runtime errors that can help you as you try to diagnose and repair the problem:

If the error message mentions SyntaxError , you know that the problem has to do with syntax: the structure of the code, the punctuation, etc.

If the program runs partway and then crashes, you know the problem is a runtime error. Programs with syntax errors don’t execute even one line.

Stay tuned for more details on the various types of runtime errors. We have a whole section of this chapter dedicated to that topic.

Check your understanding

Which of the following is a run-time error?

• Attempting to divide by 0.
• Python cannot reliably tell if you are trying to divide by 0 until it is executing your program (e.g., you might be asking the user for a value and then dividing by that value—you cannot know what value the user will enter before you run the program).
• Forgetting a right-parenthesis ) when invoking a function.
• This is a problem with the formal structure of the program. Python knows where colons are required and can detect when one is missing simply by looking at the code without running it.
• Forgetting to divide by 100 when printing a percentage amount.
• This will produce the wrong answer, but Python will not consider it an error at all. The programmer is the one who understands that the answer produced is wrong.

Who or what typically finds runtime errors?

• The programmer.
• Programmers rarely find all the runtime errors, there is a computer program that will do it for us.
• The interpreter.
• If an instruction is illegal to perform at that point in the execution, the interpreter will stop with a message describing the exception.
• The computer.
• Well, sort of. But it is a special thing in the computer that does it. The stand alone computer without this additional piece can not do it.
• The teacher / instructor.
• Your teacher and instructor may be able to find most of your runtime errors, but only because they have experience looking at code and possibly writing code. With experience runtime errors are easier to find. But we also have an automated way of finding these types of errors.

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Runtime Errors

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Runtime Errors :

• A runtime error in a program is an error that occurs while the program is running after being successfully compiled.
• Runtime errors are commonly called referred to as “bugs” and are often found during the debugging process before the software is released.
• When runtime errors occur after a program has been distributed to the public, developers often release patches, or small updates designed to fix the errors.
• Anyone can find the list of issues that they might face if they are a beginner in this article .
• While solving problems on online platforms, many run time errors can be faced, which are not clearly specified in the message that comes with them. There are a variety of runtime errors that occur such as logical errors , Input/Output errors , undefined object errors , division by zero errors , and many more.

Types of Runtime Errors :

• Division by Zero.
• Modulo Operation by Zero.
• Integer Overflow.

• Infinite Recursion or if you run out of stack memory.
• Negative array index is accessed.
• ArrayIndexOutOfBounds Exception.
• StringIndexOutOfBounds Exception.

• Accessing an array out of bounds.
• Dereferencing NULL pointers.
• Dereferencing freed memory.
• Dereferencing uninitialized pointers.
• Incorrect use of the “&” (address of) and “*” (dereferencing) operators.
• Improper formatting specifiers in printf and scanf statements.
• Stack overflow.
• Writing to read-only memory.

Ways to avoid Runtime Errors :

• Avoid using variables that have not been initialized. These may be set to 0 on your system but not on the coding platform.
• Check every single occurrence of an array element and ensure that it is not out of bounds.
• Avoid declaring too much memory. Check for the memory limit specified in the question.
• Avoid declaring too much Stack Memory . Large arrays should be declared globally outside the function.
• Use return as the end statement.
• Avoid referencing free memory or null pointers .

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Runtime Error: What It Is and How to Fix It

What to do when you see runtime errors

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A runtime error occurs while a program is running or when you first attempt to start the application. The error sometimes goes away on its own by simply reopening the app, but if not, there are a number of things you can try.

Runtime Errors

Valentin.d / Flickr

Depending on the situation, there are a few reasons why a runtime error might occur:

• There's a bug in the software.
• Memory or another system resource is in short supply.
• You've entered a foreign character into a text field, or performed some kind of action that isn't allowed.

The error usually appears as a small window, often with an indication of the program that's being affected, and sometimes with an error code and message. The prompt might also include a suggestion to contact a support team or administrator.

Here are some examples:

Paying close attention to what the error says, if possible, is the best way to address it. If the error is too general to diagnose right off the bat, then follow the below steps in order. If it's particular, however, and mentions something like Microsoft Visual C++Runtime Library, then that's the step you should start at.

How to Fix a Runtime Error

Runtime errors pop up in a variety of situations, so the possible fixes are all over the board:

Restart the computer . This is the likely solution if your computer suddenly feels like it's running much slower than usual.

Some runtime errors are caused by memory-related issues, and restarting is the quickest way to close everything that's currently running on your PC. This will free up those previously used system resources for the program that's throwing the error.

Update the program to its latest version. The runtime error might be caused by a bug that hasn't yet been patched in the release that you're using.

For example, some users report a runtime error when they use NVIDIA GeForce Experience to check for graphics card updates. In this scenario, you'd update the NVIDIA program.

You might need to re-download it from the software maker's site if there isn't a built-in method for checking for updates.

This is a good time to also check for Windows updates .

Fully delete the program, and then reinstall it . An installation that doesn't quite finish properly can be the cause of the runtime error.

The update procedure in the previous step might have done this, but if you're still getting the error, it's time to completely delete the program and confirm that it's being reinstalled from scratch.

Some uninstallers don't do a great job at erasing every remnant of the file from the registry and hard drive. Try a dedicated program uninstaller if the normal tool from the app maker doesn't fix the error.

Install the latest Microsoft Visual C++ Redistributable package . If your error says something about the runtime components of the Visual C++ libraries, this is likely solution.

Use SFC scannow to repair corrupted Windows files . The SFC command is executed in a Command Prompt window, and might be the fix for the runtime error.

Run System Restore to return your computer to a previous state. This could fix the runtime error is if it's caused by the Windows Registry being corrupt.

Reinstall Windows . If focusing on a specific program didn't fix the runtime error, or if it's interfering with the way Windows works as a whole, resetting is your last option.

How Programmers Can Prevent Runtime Errors

If you're the software maker, GeeksforGeeks suggests several ways to avoid runtime errors . Follow that link for a deeper dive into the different types of runtime errors, with examples of why they're happening and what you can do to prevent them. Some fixes include avoiding variables that haven't been initialized, and not declaring too much stack memory.

With Internet Explorer shut down for good , you won't be able to update the browser to try and fix the problem. However, if you insist on using IE rather than moving to a new web browser, check your Adobe Acrobat plugin as it may contain an error. Update Acrobat Reader if possible, or reinstall it and try opening the PDF again.

First, perform a clean boot of your Windows machine and see if that takes care of the problem. If not, you'll need to use an uninstaller program to try and get rid of the software.

First, verify that the problem is Chrome by attempting to visit the website giving you the error in a different web browser. If Chrome is the problem, clear out the cookies for that site in Chrome, restart the browser, then visit the website again. If the problem persists, check Chrome for updates .

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Examples of runtime errors in Python?

In this article, we will look at some examples of runtime errors in Python Programming Language

Runtime Errors

A runtime error in a program is one that occurs after the program has been successfully compiled.

The Python interpreter will run a program if it is syntactically correct (free of syntax errors). However, if the program encounters a runtime error - a problem that was not detected when the program was parsed and is only revealed when a specific line is executed - it may exit unexpectedly during execution. When a program crashes due to a runtime error, we say it has crashed

Some examples of Python Runtime errors

division by zero

performing an operation on incompatible types

using an identifier that has not been defined

accessing a list element, dictionary value, or object attribute which doesn’t exist

trying to access a file that doesn’t exist

Let's take a closer look at each of them by using an example

Division by zero

If we divide any number by zero, we get this error.

Algorithm (Steps)

Following are the Algorithm/steps to be followed to perform the desired task −

Take a variable to store the first input number.

Take another variable to store the second input number(Here the second number should be 0).

Divide the first number by the second number and print the result.

The following program returns the runtime error if we divide a number with zero −

On executing, the above program will generate the following output −

Because the second number is 0 and no number can be divided by 0, we get a runtime error.

Performing an operation on incompatible types

This error occurs when we perform operations like addition, multiplication, and so on on incompatible data types.

Take a string and assign some random value to it and store it in a variable.

Take an integer and assign some random integer value to it and store it in another variable.

Perform some operations such as addition on the above variables and print it.

The following program returns the runtime error if we perform operation on incompatible data types −

We can't add an integer to the string data type here, so we get a type error (runtime error).

Using an identifier that has not been defined

This error occurs when we attempt to access an identifier that has not been declared previously.

The following program returns the runtime error if we are using undefined identifier −

Because we did not define the tutorialsPoint identifier and are accessing it by printing it, a runtime error occurs (Name error).

Accessing a list element, dictionary value, or object attribute which doesn’t exist

This runtime error occurs when we attempt to access a non-existent list,string,dictionary element/index.

When we attempt to use an index that does not exist or is too large, it throws an IndexError .

Create a list and assign some random values to it.

Access the list element by index by giving the index that doesn’t exist and printing it.

The following program returns the index error if we access an element out of range −

There are 5 elements in the list, and we are attempting to access the 10th index, which does not exist, resulting in an index error.

Trying to access a file that doesn’t exist

If we try to open a file that doesn't exist, it throws a runtime error.

Create a variable to store the path of the text file. This is a fixed value. In the example below, this value must be substituted with the file path from your own system.

Use the open() function(opens a file and returns a file object as a result) to open the text file in read-only mode by passing the file name, and mode as arguments to it (Here “r” represents read-only mode)

Print it value of the given file.

The following program returns the file not found error if we access an file that doesn’t exist −

We learned about runtime errors in Python in this article. We also used examples to explain the most common Python runtime errors.

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Fix Python RecursionError: Maximum Recursion Depth Exceeded

You might have seen a Python recursion error when running your Python code. Why does this happen? Is there a way to fix this error?

A Python RecursionError exception is raised when the execution of your program exceeds the recursion limit of the Python interpreter. Two ways to address this exception are increasing the Python recursion limit or refactoring your code using iteration instead of recursion.

Let’s go through some examples so you can understand how this works.

The recursion begins!

RecursionError: Maximum Recursion Depth Exceeded in Comparison

Let’s create a program to calculate the factorial of a number following the formula below:

Write a function called factorial and then use print statements to print the value of the factorial for a few numbers.

This is a recursive function…

A recursive function is a function that calls itself. Recursion is not specific to Python, it’s a concept common to most programming languages.

You can see that in the else statement of the if else we call the factorial function passing n-1 as parameter.

The execution of the function continues until n is equal to 0.

Let’s see what happens when we calculate the factorial for two small numbers:

After checking that __name__ is equal to ‘__main__’ we print the factorial for two numbers.

It’s all good.

But, here is what happens if we calculate the factorial of 1000…

The RecursionError occurs because the Python interpreter has exceeded the recursion limit allowed.

The reason why the Python interpreter limits the number of times recursion can be performed is to avoid infinite recursion and hence avoid a stack overflow.

Let’s have a look at how to find out what the recursion limit is in Python and how to update it.

What is the Recursion Limit in Python?

Open the Python shell and use the following code to see the value of the recursion limit for the Python interpreter:

Interesting…the limit is 1000.

To increase the recursion limit to 1500 we can add the following lines at the beginning of our program:

If you do that and try to calculate again the factorial of 1000 you get a long number back (no more errors).

That’s good! But…

…this solution could work if like in this case we are very near to the recursion limit and we are pretty confident that our program won’t end up using too much memory on our system.

How to Catch a Python Recursion Error

One possible option to handle the RecursionError exception is by using try except.

It allows to provide a clean message when your application is executed instead of showing an unclear and verbose exception.

Modify the “main” of your program as follows:

Note : before executing the program remember to comment the line we have added in the section before that increases the recursion limit for the Python interpreter.

Now, execute the code…

You will get the following when calculating the factorial for 1000.

Definitely a lot cleaner than the long exception traceback.

Interestingly, if we run our program with Python 2.7 the output is different:

We get back a NameError exception because the exception of type RecursionError is not defined .

Looking at the Python documentation I can see that the error is caused by the fact that the RecursionError exception was only introduced in Python 3.5:

So, if you are using a version of Python older than 3.5 replace the RecursionError with a RuntimeError.

In this way our Python application works fine with Python2:

How Do You Stop Infinite Recursion in Python?

As we have seen so far, the use of recursion in Python can lead to a recursion error.

How can you prevent infinite recursion from happening? Is that even something we have to worry about in Python?

Firstly, do you think the code we have written to calculate the factorial could cause an infinite recursion?

Let’s look at the function again…

This function cannot cause infinite recursion because the if branch doesn’t make a recursive call . This means that the execution of our function eventually stops.

We will create a very simple recursive function that doesn’t have an branch breaking the recursion…

When you run this program you get back “RecursionError: maximum recursion depth exceeded”.

So, in theory this program could have caused infinite recursion, in practice this didn’t happen because the recursion depth limit set by the Python interpreter prevents infinite recursion from occurring .

How to Convert a Python Recursion to an Iterative Approach

Using recursion is not the only option possible. An alternative to solve the RecursionError is to use a Python while loop.

We are basically going from recursion to iteration.

Firstly we set the value of the factorial to 1 and then at each iteration of the while loop we:

• Multiply the latest value of the factorial by n
• Decrease n by 1

The execution of the while loop continues as long as n is greater than 0.

I want to make sure that this implementation of the factorial returns the same results as the implementation that uses recursion.

So, let’s define a Python list that contains a few numbers. Then we will calculate the factorial of each number using both functions and compare the results.

We use a Python for loop to go through each number in the list.

Our program ends as soon as the factorials calculated by the two functions for a given number don’t match.

Let’s run our program and see what we get:

Our implementation of the factorial using an iterative approach works well.

In this tutorial we have seen why the RecursionError occurs in Python and how you can fix it.

Two options you have are:

• Increase the value of the recursion limit for the Python interpreter.
• Use iteration instead of recursion.

Which one are you going to use?

Claudio Sabato is an IT expert with over 15 years of professional experience in Python programming, Linux Systems Administration, Bash programming, and IT Systems Design. He is a professional certified by the Linux Professional Institute .

With a Master’s degree in Computer Science, he has a strong foundation in Software Engineering and a passion for robotics with Raspberry Pi.

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Mastering Slash Commands with GitHub Copilot in Visual Studio

Cynthia Zanoni

Laurent Bugnion

May 14th, 2024 1

GitHub Copilot, the AI-powered coding assistant, revolutionizes coding in Visual Studio with its advanced features. In this series, we delve into the efficiency and convenience offered by Slash Commands, elevating your coding workflow.

Introducing Slash Commands

Slash Commands are predefined actions within GitHub Copilot, accessible through the prompt interface. Bruno Capuano, in his latest video, elucidates these commands, accessible via the Slash button in the Copilot Chat window or by typing a forward slash in the message box.

Alternatively, you can also access the Slash Commands by typing a forward slash in the message box.

Key commands include:

• doc : Insert a documentation comment in the current cursor position.
• exp : Start a new conversation thread with a fresh context.
• explain : Provide an explanation for the selected code.
• fix : Suggest fixes for code errors and typos.
• generate : Generate new code snippets based on your input.
• optimize : Recommend code optimizations to improve performance.
• tests : Create a unit test for the current code selection.
• help : Access help and support for GitHub Copilot.

A Practical Example with /fix

Demonstrating the power of Slash Commands, the /fix command automatically suggests corrections for typos and errors, enhancing code quality and efficiency.

In the video, Bruno demonstrates how GitHub Copilot can automatically suggest corrections for typos and other issues. This command can be used in the main chat window, and it’s also accessible in the inline chat by pressing Alt-Slash (Alt-/) or through the right-click context menu.

As you can see, these Slash Commands can significantly improve your productivity in Visual Studio. Learn how to Install GitHub Copilot in Visual Studio .

Additional Resources

To learn more about GitHub Copilot and Slash Commands, check out our resource collection here. You can watch the full video here . For ongoing updates, stay tuned to this blog and consider subscribing to our YouTube channel for more insights and tutorials.

• Code Faster and Better with GitHub Copilot’s New Features: Slash Commands and Context Variables
• Announcing the GitHub Extension for Visual Studio

Cynthia Zanoni Cloud Advocate, Developer Relations

Laurent Bugnion Principal Cloud Advocate, Developer Relations