Integration with FreeCAD 26.3: Errors

Help & Troubleshooting
1

I get the following errors on a fresh FreeCAD 26.3 installation (no older FreeCAD versions were installed).

I “Installed” the Rotatrix integration while FreeCAD was closed. When I start FreeCad it shows the errors shown in the image.

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2

Thanks, I’ve had another report of the same issue with FreeCAD 26.3 pre-releases. I believe they’ve changed the Python version and there is some conflict. Can you use FreeCAD 1.1.x for the time being? I’ll need to update the integration.

3

Yes, I can use FreeCAD 1.1.x until this is fixed.

4

This turns out to be a confirmed FreeCAD 26.3 RC1 Windows packaging bug. It ships Python 3.13.15 with an outdated ssl.py, causing the RAND_pseudo_bytes error when Rotatrix loads. FreeCAD has fixed this upstream.

Until they release the fix, here is a local workaround you can do:

  1. Close FreeCAD.
  2. Open your FreeCAD installation folder, then bin\Lib.
  3. Rename ssl.py to ssl.py.bak as a backup.
  4. Download the official Python 3.13.15 ssl.py and save it in that folder as ssl.py. Make sure the filename isn’t ssl.py.txt. Windows may ask for administrator permission.
  5. Restart FreeCAD.

Then try Rotatrix again. Please let me know whether this resolves it for you. You can undo the change by restoring ssl.py.bak.

Alternatively, continue using FreeCAD 1.1.x until a corrected 26.3 build is available.

FYI: You can also try this in the View > Panels > Python Console to confirm the cause and fix. It fails until the fix above is applied.

import ssl
print(ssl.OPENSSL_VERSION)
5

Excellent! I updated ssl.py (i.e. followed steps 1-5 in your post) and Rotatrix works fine now in FreeCAD 26.3 RC1 (Windows).

Thanks for the quick and detailed answer.