Fusion
In the next MAJOR Fusion 360 update the embedded python interpreter will be upgraded to Python 3.9.7.
If you write or use any Python apps delivered as .pyc files, this change will break them!
It will be broken because .pyc files are tied to the version of Python used to create them. Add-ins compiled with the current version of Python (3.7) will not be compatible with the updated Python (3.9) and will fail to load. This change does not affect any add-ins where the .py source code is available.
Timeline (exact dates are subject to change)
February 8: Users of add-ins that contain precompiled python files (.pyc) will receive a warning message that the add-in they are running will not be compatible with the next version of Fusion 360. There will be a link to this help page article. (Note: it should be published today or tomorrow). They will be instructed to download a new version of the add-in from the app store or from the developer directly.
March 29th: Users of add-ins that contain precompiled python files (.pyc) will receive an error stating that the version of the add-in they are using is no longer compatible. It will link to the same help article as above.
What you need to do
Again, if your app does not distribute PRECOMPILED PYTHON (.pyc) you likely have no action.
If you are developing an add-in that you use personally or internally at your company, you can simply re-compile after the new version of Fusion 360 is available.
If you develop an app that is distributed directly to customers or is available on the Autodesk App Store you will need to create a new version of your add-in for distribution.
There are two options to begin this process:
- Sign up for the Fusion Insider Program. This should give you access to the March release about ~2 weeks before public launch. This will have the new version of Python and you can compile and test your new add-in version.
- Install a local copy of Python 3.9.7 and compile your code. The challenge here is that you will not be able to test directly in the current version of Fusion 360 as 3.0 compiled .pyc files will not run in 3.7. If it is absolutely necessary, you could at least ensure code compatibility and that there are not build failures before the Early Access version (above) is available.
If you distribute your app through the App Store it is important that you begin the submission process as soon as possible after the Early Access version is available to ensure there is enough time to create installers, test, sign and publish your app.
The App Store team is aware of the issue and any app submissions (new or updated) that fall into this category will be held for release until the day the new Fusion 360 version goes live.
Some notes on Python 3.9
In general most scripts and add-ins written with python 3.7 should be compatible, but you should still consult the documentation and test when the new version is available.
There are also a few nice features that have been added in the Python 3.8 and 3.9 updates.
See below for a summary of the changes and enhancements:
https://docs.python.org/3.9/whatsnew/3.8.html
https://docs.python.org/3.9/whatsnew/3.9.html
Patrick Rainsberry
Developer Advocate, Fusion 360
