# Big Sur prise? Bug Surprise?

**URL:** <https://forum.xojo.com/t/big-sur-prise-bug-surprise/59747>\
**Category:** macOS\
**Created:** [December 12, 2020, 11:38pm UTC](https://forum.xojo.com/t/big-sur-prise-bug-surprise/59747 "2020-12-12T23:38:43Z")\
**Posts on this page:** 1\
**Showing post:** 38

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**Author:** ![Lars\_Brennicke](https://forum.xojo.com/letter_avatar_proxy/v4/letter/l/82dd89/32.png) [@Lars\_Brennicke](https://forum.xojo.com/u/Lars_Brennicke)\
**Post date:** [November 7, 2021, 2:06pm UTC](https://forum.xojo.com/t/big-sur-prise-bug-surprise/59747/38 "2021-11-07T14:06:44Z")

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I ran into this problem today when I wanted to use an older version of Xojo (2018 R4) on Monterey. I found a simple solution that works at least for running the app from Xojo. I could not test if it also works for building Mac apps, because I don’t have a desktop license. Obviously, the better solution is probably to modify your code so that it runs with a more recent version of Xojo (and buy the Xojo upgrade if necessary).

- Run the Xojo app at least once, so that Gatekeeper is out of the way and you can modify Xojo.
- Right-click the Xojo app and choose “Show package contents”.
- Go to the folder Contents/Resources/SDKStubs/macosx10.14/System/Library/Frameworks/AppKit.framework
- Open the file AppKit.tbd with a text editor like BBEdit.
- Under “reexports”, you’ll find the problematic UIFoundation framework that’s referenced in the error message from the linker (/System/Library/PrivateFrameworks/UIFoundation.framework/Versions/A/UIFoundation).
- Simply remove this text (/System/Library…) and the preceding comma. Don’t delete the closing bracket, it should now be where the deleted comma used to be.
- Save the file.

Now Xojo will run your apps again.

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