Python Language Tutorial => Custom Exception

Example

Here, we have created a user-defined exception called CustomError which is derived from the Exception class. This new exception can be raised, like other exceptions, using the raise statement with an optional error message.

class CustomError(Exception):
       pass

x = 1

if x == 1:
    raise CustomError('This is custom error')

Output:

Traceback (most recent call last):
  File "error_custom.py", line 8, in <module>
    raise CustomError('This is custom error')
__main__.CustomError: This is custom error