Troubleshooting - kdaisho/Blog GitHub Wiki

Launching mitmproxy fails due to an error

(trapped) error reading bcrypt version

File "/usr/lib/python3/dist-packages/passlib/handlers/bcrypt.py", line 619, in _load_backend_mixin
    version = _bcrypt.__about__.__version__

This is because passlib expects bcrypt version 4.0.1. The latest version of bcrypt (4.2.0 at Feb 2025) doesn't have about attribute.

I fixed this by patching passlib as follows:

Open the file:

sudo vim `/usr/lib/python3/dist-packages/passlib/handlers/bcrypt.py`

Replace this:

version = _bcrypt.__about__.__version__

With this:

version = getattr(_bcrypt, '__version__', '<unknown>')

This is not the best solution as upgrading the language will overwrite it, but it does the job for now.

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