How to Ignore Errors and Exceptions in Python with try...except pass
While the primary purpose of try...except
blocks in Python is to handle errors gracefully, sometimes you might want to intentionally ignore certain exceptions, allowing your program to continue even if a specific operation fails.
This guide explains how to use the pass
statement within an except
block to achieve this, and crucially, why it's important to catch specific exceptions rather than using a bare except:
.
Ignoring Exceptions with except: pass
(Use with Caution)
You can use a bare except:
block followed by the pass
statement to catch and effectively ignore any exception that occurs within the try
block.
my_list = []
try:
# This line will raise an IndexError
print(my_list[100])
except:
# The pass statement does nothing, effectively ignoring the error
pass
print("Program continues after the try...except block.") # This will be printed
- The
try
block attempts to execute the code within it. - If any exception occurs (like
IndexError
orValueError
in the examples below), theexcept:
block catches it. - The
pass
statement is a null operation, i.e. it does nothing. The program simply continues executing after thetry...except
block.
my_list = []
try:
# This line will raise a ValueError
my_list.remove(1000) # 1000 is not in the list
except:
pass # Ignore the ValueError
print("Program still continues.")
Warning: Using a bare except:
is generally strongly discouraged.
It catches all possible exceptions, including critical ones like SystemExit
or KeyboardInterrupt
(when you press Ctrl+C), and can hide unexpected bugs in your code, making debugging much harder. You might accidentally ignore errors you didn't intend to.
Ignoring Specific Exceptions with pass
(Recommended)
The better practice is to explicitly catch only the specific exception(s) you anticipate and want to ignore:
my_list = []
try:
# This line will raise an IndexError
print(my_list[100])
except IndexError:
# Only ignore IndexError
pass
print("Program continues...") # This will be printed
# Example where a different error occurs and is NOT ignored:
try:
result = 25 / 0 # This will raise a ZeroDivisionError
except IndexError:
# This block will NOT run for ZeroDivisionError
pass
# The program would likely terminate here with an unhandled ZeroDivisionError
print("This line might not be reached if ZeroDivisionError is unhandled.")
- By specifying
except IndexError:
, you ensure that onlyIndexError
exceptions are caught and ignored. - Other unexpected errors (like
ZeroDivisionError
in the secondtry
block) will still be raised, alerting you to potential problems.
Ignoring Multiple Specific Exceptions
You can catch multiple specific exceptions in a single except
block by providing them as a tuple:
my_list = []
try:
# This line will raise a ZeroDivisionError
print(25 / 0)
except (IndexError, ZeroDivisionError):
# Ignore either IndexError OR ZeroDivisionError
pass
print("Program continues...") # This will be printed
- The
except (IndexError, ZeroDivisionError):
block will catch either anIndexError
or aZeroDivisionError
, but no other types of exceptions.
When to Ignore Exceptions (and When Not To)
Ignoring exceptions with pass
should be done cautiously. Legitimate use cases include:
- Optional Operations: When an operation might fail, but the failure isn't critical to the main flow (e.g., attempting to delete a file that might not exist).
- Resource Cleanup (in
finally
): Sometimespass
might appear in afinally
block'sexcept
clause during cleanup, although more specific logging is usually better.
Avoid ignoring exceptions when:
- You don't understand why the exception might occur.
- The exception indicates a serious problem that should be fixed.
- You could handle the exception more gracefully (e.g., by providing a default value, logging the error, or retrying).