Question: After downgrading from Xcode 4.2 beta to Xcode SDK 4.02 I am facing new error messages: – “gcc-4.2: error trying to exec ‘/Developer/Platforms/iPhoneSimulator.platform/Developer/usr/bin/arm-apple-darwin10-gcc-4.2.1’: execvp: No such file or directory”, and – “Command /Developer/Platforms/iPhoneSimulator.platform/Developer/usr/bin/gcc-4.2 failed with exit code 255”. What’s is this for and what to do now? Answer: Check out your build configuration. The Architectures probably have an inherited $(ARCHS_…) value which can fire a build error: 1. Navigate to Build Settings in Xcode and check out values in the Architectures group. 2. Remove “VALID ARCH” entry from Architectures field to reset settings. Use $(ARCHS_STANDARD_32_BIT) , or armv6, armv7 values as you wish. $(ARCHS_STANDARD_32_BIT) should show armv6 armv7. 3. Repeat these steps at your dependent projects.