Flask-Session can't import want_bytes from itsdangerous

Question

I am using Flask-Session and recently installed or upgraded to itsdangerous 1.0.0. Now I get the error ImportError: cannot import name \'want_bytes\'. Why is this e

Answer 1

itsdangerous 1.1.0 contains a temporary fix for this. You can upgrade itsdangerous and continue to use Flask-Session right now. There is no need to pin to itsdangerous==0.24.

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itsdangerous 1.0.0 was recently released, removing non-public top-level imports. Flask-Session appears to have been using such an import, from itsdangerous import want_bytes.

This has been reported to Flask-Session and a fix will hopefully be released eventually.

Answer 2

The file structure of the itsdangerous package has changed. The function resides in the session.py file. Changing the import statements from:

from itsdangerous import Signer, BadSignature, want_bytes

to

from itsdangerous import Signer, BadSignature
from itsdangerous.encoding import want_bytes

works for me.