After updating my system to macOS Tahoe 26.1 and Xcode 26.1, all breakpoints in my project fail to work. When I run the application in Debug mode, any enabled breakpoint (blue) immediately becomes disabled (grayed out) the moment the app launches. The application runs, but the debugger never stops.
This issue occurs in any location, including in the application's init() method, which should always be hit. This behavior suggests that the LLDB debugger is failing to attach to the process at launch or is being instructed not to enable breakpoints.
System Configuration:
Mac Model: MacBook Pro 14" (2021), Apple M1 Pro macOS Version: Tahoe 26.1 Xcode Version: 26.1 Project Type: SwiftUI App for macOS Troubleshooting Steps Performed (All Unsuccessful):
We have performed an extensive series of troubleshooting steps to resolve the issue, none of which have worked. These steps include:
- Basic Project Cleaning:
- Cleaned the build folder (Product > Clean Build Folder).
- Deleted the entire DerivedData directory.
- Deleted the project's xcuserdata folder.
- Xcode & System Procedures:
- Restarted Xcode multiple times.
- Rebooted the Mac multiple times.
- Reinstalled Xcode Command Line Tools using xcode-select --install.
- Reset the Xcode path using sudo xcode-select --reset and sudo xcode-select -s /Applications/Xcode.app/Contents/Developer.
- Forced an update of the system's shared cache with xcrun simctl runtime dyld_shared_cache update --all.
- Project Build Settings Verification (for Debug configuration):
- Build Configuration: Verified that the "Run" scheme is set to Debug.
- Optimization Level: Confirmed it is set to No Optimization [-O0].
- Debug Information Format: Confirmed it is set to DWARF with dSYM File.
- Strip Swift Symbols: Confirmed it is set to No. (This was a new setting noticed after the Xcode update).
- Enable Hardened Runtime: Attempted setting this to both Yes and No. The issue persists in both cases.
- Validate Workspace: Confirmed it is set to Yes.
- Code Signing:
- Verified that "Automatically manage signing" is enabled with a valid team.
- Manually deleted and re-created the "Apple Development" certificates via Xcode's Accounts settings.
- Direct LLDB Testing:
- Created a ~/.lldbinit file.
- Using breakpoint list, confirmed that LLDB starts with "No breakpoints currently set," indicating that Xcode is likely not passing the breakpoints to the debugger.
- Using settings set target.process.stop-on-entry true, confirmed that the app still does not stop on entry, suggesting the debugger is failing to attach to the process at all.
Conclusion:
Given that all standard and advanced troubleshooting steps have failed, and the issue started immediately after updating both macOS and Xcode to a non-public release (Tahoe 26.1 / Xcode 26.1), this appears to be a regression or a bug in the new development environment. The failure of stop-on-entry strongly suggests a fundamental issue with the debugger attachment process on this specific OS and Xcode combination.