Xcode 9.4 : unexpected service error: The Xcode build system has crashed
Update for Xcode 13.4.1:
I had this infamous bug today as well. I tried a lot including clean project, delete derived, restart max etc.
What did the fix finally is similar to the answer of kakaiikaka: I set the workspace settings to "Legacy Build System (Deprecated)" for both, the shared and per user workspace. I tried to build with this, but got an error because I had packages wich are not supported. Restarted Xcode, then changed back the build system. Restarted Xcode again. Now the crash doesn't happen any more.
Looks like something internal was spoilt and cycling the build system fixed it.
I moved a lot of files all at once between folders, including nested folders. This error started happening. Nothing I did in regards to cleaning, purging derived data, or undoing the move operation would help.
What I did to help was: restore the previous version of the project file from source control and then re-add all the applicable new files to it. It was project file related. Deleting user data inside the project container did not help in my case. So as long as you use source control and can rollback the .xcodeproj, this may be an option.
This error usually happens between Xcode major versions. Apple usually claim their new build system is ** times faster than their previous version. If you see this error(I see this on changing Xcode9 to Xcode10 beta), you can always change it to the legacy build system. Here is how you can do this:
- Open 'workspace settings'( it is now changed to 'Project Settings' if you are using Xcode10 or later) in the File Menu
- Change build system to 'legacy'
Please clear derived data folder (located at ~/Library/Developer/Xcode/DerivedData) and restart the Xcode project.