all Python 3tracebackfunction

traceback.format_exc()

formatting tracebacks

The traceback of the exception being handled as one string — what a crash prints, but in a variable: for a log, a file or an email.

Syntax

text = traceback.format_exc(limit=None, chain=True)

It only works inside an except block (or a function called from one): outside handling it returns the string 'NoneType: None\n' rather than failing, and an empty report is easy to miss. If the exception was raised inside another except, the text includes the first one too, after "During handling of the above exception…"; chain=False keeps only the last. For logging, logger.exception('…') is shorter: it appends the same traceback itself.

Examples

import traceback
try:
    1 / 0
except ZeroDivisionError:
    text = traceback.format_exc()
print(text.splitlines()[0])  # → Traceback (most recent call last):
print(text.splitlines()[-1])  # → ZeroDivisionError: division by zero

import traceback
print(repr(traceback.format_exc()))  # → 'NoneType: None\n'

See also

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