Sounds like you have updated to Catalina after already having the IXEG 737 Classic installed, which means your uninstaller is from old architecture that Apple no longer supports. In this situation you will need to take the following steps: 1. Go to X-Plane/X-Aviation folder and delete the following file: Uninstall IXEG 737 Classic 2. Go to X-Plane/Aircraft/ and delete the following folder: IXEG 737 Classic 3. Re-run the IXEG installer That should have you back up and running!