I have the same issue, too. Xcode 15.2 (15C500b), macOS 14.2.1 (23C71). Also tried to fix it by steps mentioned above and it didn't work

@ikiwi, by the way, it seems that Apple knows about this issue and they're working on it (https://forums.developer.apple.com/forums/thread/739914?answerId=776922022#776922022). There seems to be a workaround on that which worked for me (https://forums.developer.apple.com/forums/thread/744108?answerId=776845022#776845022)

Seeing the same issue — the breakpoints successfully stop the execution, but when I try to inspect something with po myVariable, the Xcode aborts app execution with the following in the console: Couldn't find the Objective-C runtime library in loaded images. Message from debugger: The LLDB RPC server has crashed. You may need to manually terminate your process. The crash log is located in ~/Library/Logs/DiagnosticReports and has a prefix 'lldb-rpc-server'. Please file a bug and attach the most recent crash log. I've started observing these issues after updating to macOS 15.4 on Friday, April 4th macOS 15.4 (24E248) Xcode 16.3 (16E140) and Xcode 16.2 (16C5032a)