Blog |

How to Fix ValueError Exceptions in Python

How to Fix ValueError Exceptions in Python
Table of Contents

The Python ValueError is an exception that occurs when a function receives an argument of the correct data type but an inappropriate value. This error usually occurs in mathematical operations that require a certain kind of value.

What Causes ValueError

The Python ValueError is raised when the wrong value is assigned to an object. This can happen if the value is invalid for a given operation, or if the value does not exist. For example, if a negative integer is passed to a square root operation, a ValueError is raised.

Python ValueError Example

Here’s an example of a Python ValueError raised when trying to perform a square root operation on a negative number:

import math


In the above example, a negative integer is passed to the math.sqrt() function. Since the function expects a positive integer, running the above code raises a ValueError:

Traceback (most recent call last):
  File "", line 3, in <module>
ValueError: math domain error

How to Fix ValueError Exceptions in Python

To resolve the ValueError in Python code, a try-except block can be used. The lines of code that can throw the ValueError should be placed in the try block, and the except block can catch and handle the error.

Using the above approach, the previous example can be updated to handle the error:

import math

except ValueError:
    print('Positive number expected for square root operation')

Here, a check is performed for the ValueError using the try-except block. When the above code is executed, the except block catches the ValueError and handles it, producing the following output:

Positive number expected for square root operation

Track, Analyze and Manage Errors With Rollbar

Managing errors and exceptions in your code is challenging. It can make deploying production code an unnerving experience. Being able to track, analyze, and manage errors in real-time can help you to proceed with more confidence. Rollbar automates error monitoring and triaging, making fixing Python errors easier than ever. Try it today!

Related Resources

"Rollbar allows us to go from alerting to impact analysis and resolution in a matter of minutes. Without it we would be flying blind."

Error Monitoring

Start continuously improving your code today.

Get Started Shape