Module compiled with Swift 5.3 cannot be imported by #1
Description
You need to set the Build Libraries for Distribution option to Yes in your framework's build settings, otherwise, the swift compiler doesn't generate the necessary .swiftinterface files which are the key to future compilers being able to load your old library.
This ends up in your project.pbxproj file as:
BUILD_LIBRARY_FOR_DISTRIBUTION = YES;
After setting this flag, a framework I compiled using Xcode 11.0 (swift 5.1) was able to be used by Xcode 11.2 (swift 5.1.2) and everything appears to be working correctly.
If the error still persists go to Product > Clean Build Folder and Build again.
Turns out if you watch the WWDC video, they explain it: https://developer.apple.com/videos/play/wwdc2019/416/