Python/Flask error: “ImportError: cannot import name _compare_digest”

Question

With Windows, I am following this Flask tutorial when I came across the following error:

C:\\Users\\Gregory Gundersen\\Documents\\Research\\flask-test>pyt         


        

Answer 1

You appear to have half the changes made for issue 21306 (backporting hmac.compare_digest to 2.7).

Your hmac module has the lines:

from operator import _compare_digest as compare_digest

at the top, but your sys.version_info shows you are running Python 2.7.6; quoting our quick chat session:

Me: Next simple check:

import sys
print(sys.version_info)

You: sys.version_info(major=2, minor=7, micro=6, releaselevel='final', serial=0)

The hmac version you have is for Python 2.7.7 and up, however!

You'll want to reinstall your Python; download 2.7.8 and reinstall it to make sure you have the correct binary executable for your standard library files.

Answer 2

This can occur when you have updated python without rebuilding your virtualenv. In this case, just regenerate your virtualenv.