Big Sur prise? Bug Surprise?

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.