How to print the stack trace of an exception object in Python?

Question

Note that the question is NOT about printing stack trace of LAST exception. Exception object may be saved at some distant point of time in the past.

Similar: https://stackoverflow.com/questions/3702675/how-to-print-the-full-traceback-without-halting-the-program — user202729, Oct 10 '18 at 14:48

score 46 · Accepted Answer · answered Oct 10 '18 at 14:39

46

It's a bit inconvenient, but you can use traceback.print_exception. Given an exception ex:

traceback.print_exception(type(ex), ex, ex.__traceback__)

Example:

import traceback

try:
    1/0
except Exception as ex:
    traceback.print_exception(type(ex), ex, ex.__traceback__)

# output:
# Traceback (most recent call last):
#   File "untitled.py", line 4, in <module>
#     1/0
# ZeroDivisionError: division by zero

answered Oct 10 '18 at 14:39

Aran-Fey

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1

It's a bit inconvenient why? looks okay to me – Jean-François Fabre Oct 10 '18 at 16:36
8

@Jean-FrançoisFabre Well, there really is no reason why it's necessary to pass *3* arguments to that function. If a function like `print_exception(ex)` existed, that would be much nicer. – Aran-Fey Oct 10 '18 at 16:48
1

Other useful function would be `print_exc()` which get info about exception(s) from `sys.info` – Alex Pshenko Oct 02 '19 at 12:32
See also [`traceback.format_exc()`](https://docs.python.org/2/library/traceback.html) – matanster Aug 08 '20 at 13:45
IMHO, `exception.traceback()` is a more cleaner OOPs-like syntax. – Nishant Apr 16 '22 at 13:51
`traceback` doesn't work in many cases. For example if python code is invoked from shared library. @Jean-FrançoisFabre answer is correct. – user36313 Sep 08 '22 at 11:46

score 4 · Answer 2 · answered Oct 10 '18 at 14:46

you can manually iterate through the __traceback__ attribute to print lines & files:

def function():
    raise ValueError("flfkl")

try:
    function()
except Exception as e:
    traceback = e.__traceback__
    while traceback:
        print("{}: {}".format(traceback.tb_frame.f_code.co_filename,traceback.tb_lineno))
        traceback = traceback.tb_next

How to print the stack trace of an exception object in Python?

2 Answers2

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