When building as described above, the helper crashes in such a way (Termination Reason: CODESIGNING 4 Launch Constraint Violation) that suggests I need to apply launch constraints to resolve the problem. I had not previously had launch constraints in my project.

I'm only attempting to apply launch constraints because it seems to be the remedy to the helper/daemon crash. If there is a simpler remedy (like a new build setting I'm missing in XCode 26?) that would be even better. Mainly, I'm confused as to why building with XCode 26 and linking with macOS 26 would cause a crash with that code signing reason when previously it did not.

Sounds good. Here is the crash report: com.myCompany.myDaemon-2025-09-15-081339.txt

Thanks for the feedback! No launch constraints in the codesign output, and the codesigning matches between app and daemon. I moved the app to /Applications and the issue persists. Alas, I'm still confused...

If it's relevant, the daemon relies on several frameworks that we also build from the same project. The frameworks are stored in the main app.

The problem ended up being solved by calling: sfltool resetbtm in Terminal, followed of course by a restart on each affected machine. Interesting that it occurred across several machines all running macOS 13 and 14 right when we updated to Xcode 26. It does seem like the system will occasionally get upset with big changes to the app through the development cycle.