We’re running unit tests in the CI flow for our iOS products. One day the CI builds started failing with hundreds of lines of the following: profiling:invalid arc tag (0x0000000c) profiling:invalid arc tag (0x43555b2d) profiling:invalid arc tag (0x0000000c) profiling:invalid arc tag (0x43555b2d) profiling:invalid arc tag (0x0000000c) profiling:invalid arc tag (0x614d534e) profiling:invalid arc tag (0x5f787863) profiling:invalid arc tag (0x00000000) profiling:invalid arc tag (0x00000000) ** TEST FAILED ** But there were no actual failures in any of the tests.Turns out the thing to do is to clean out the derived data folder ( default: ~/Library/Developer/Xcode/DerivedData ) Problem solved 🙂 //