Debug Failed in Xcode Simulator

macOS 15.4 + Xcode 16.x – Breakpoints completely broken, LLDB crashes

Just upgraded to macOS 15.4 and started running into a serious issue with breakpoints in Xcode 16.2 (also tested 16.1 and 16.3). Basically, whenever a breakpoint is hit, Xcode fails with this error:

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.

After this, the build just stops, no breakpoint is hit, and no stack trace is shown. Debugging becomes completely unusable.

I’ve confirmed this happens consistently across multiple Xcode versions after upgrading to macOS 15.4. Seems like the update broke something deep in the debugger/LLDB internals.

Workaround

The only way I’ve been able to get around it is to run the app on a physical device instead of the simulator. That seems to avoid the crash (for now).

Saw a few threads mentioning that macOS 15.5 Beta might fix this issue—but unfortunately, I can’t install betas due to company policy.

Just wanted to put this out there in case others are seeing the same thing, or have found a better workaround. Also curious if Apple is aware or if anyone’s had luck filing a radar.

I found a way to fix the debugging issue by deleting all Xcode-related folders and reinstalling Xcode and command-line tools. However, I'm not sure what exactly solved it. Here are my steps:

1. Deleted the following folders/files:

/Library/Developer/CommandLineTools
/Applications/Xcode.app
/Library/Preferences/com.apple.dt.Xcode.plist
~/Library/Preferences/com.apple.dt.Xcode.plist
~/Library/Caches/com.apple.dt.Xcode
~/Library/Application Support/Xcode
~/Library/Developer/* # except /Xcode/UserData and /Xcode/Archives

1. Reboot
2. Install Xcode 16.3 from dmg, run it, accept all agreements, etc.
3. Run xcode-select --install to install Command Line Tools for Xcode

After all these steps, breakpoints set while running the app in the Simulator no longer freeze the Simulator/debugger.

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)

Same error Xcode 16.3

I tested macOS 15.4 (24E248), Xcode Version 16.3 (16E140) - issue is here. UPD After a complete reinstallation Xcode, following the instructions provided by @podkovyr , the issue has been resolved!

TL;DR, updating to Xcode 16.3 fixed it for me.

This broke for me as well in Xcode 16.2, and I did the normal dance of reseting simulators, restarting Xcode, restarting computer, and nuking derived data, etc. etc. ... but once I upgraded to 16.3, everything works again

After a few tests, as someone mentioned in the thread, I realized that the error was not occurring on my iPhone 15 Pro running iOS 18.4. The solution: -Install Xcode 16.3 -Install iOS 18.4 -Open Xcode 16.2 and launch a simulator with iOS 18.4

P.S.: My project isn't compiling in Xcode 16.3 — that's a problem for future me.

I can't debug or reliably stay connected on 16.2 and 16.3 on the latest Mac OS

I found 16.2 with 18.3 is sometimes stable, but others completely unusable. 16.2 with 18.4 seems slightly more stable

Xcode 16.3 is one of the most buggy updates I've ever experienced. I had to downgrade and revert the upgrade to 16.2.

Xcode 16.3 and macOS 15.4 were completely unusable for our project.

What works for me in our project is XCode 16.2 and macOS 15.4 running on real device

I came here because I finally upgraded to Sequoia 15.4 yesterday, but was still on Xcode 16.2, and was experiencing these crashes.

Upgraded to Xcode 16.3, but did not help.

After reading here, I decided to install Sequoia Beta 15.5 (24F5042g), and the problem disappeared.

I did not try @podkovyr 's way to fix (deleting Xcode fully, including its caches, then reinstalling Xcode). But I expect that to be a working solution as well.

The reason why I expect so is that I had noticed for a long time that the time between pressing the 'Start' button and the debugger connecting had been increasing to quite some time, over time. But now that I have Macos 15.5 Beta and Xcode 16.3, I notice that starting and debugging the app is very fast again. I suspect that some or more cache files were growing out of hands. I have no proof, just a suspicion. But it doesn't matter because the issue seems to be resolved now.

Deleting all the simulators and reinstalling them fixed it for me.

same issue here

macOS 15.4 (24E248)

Xcode 16.0 (16A242d) &16.2 (16C5032a) run any simulator will hit

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.

Same problem here:

XCode 16.1 (16B40) macOS 15.4 (24E248) simulator: 18.0 and 18.2

Actually fixed it by deleting the XCode. Redownloaded and running on simulator 18.4.

Has anyone been able to produce a minimum reproducible sample project, perhaps shared on GitHub, to demonstrate this issue?

I find that I can only replicate this issue in my existing project, and not when creating an entirely new project.