If your iOS build fails with error: Invalid bitcode version (Producer: '802.0.38.0_0' Reader: '800.0.42.1_0'), this error means that you are using a lib or pod that was built by a newer version of Xcode than the Xcode version currently used in your project.
To fix the error, update your project and the build configuration in App Center to use a newer version of Xcode or switch to an alternate, older version of the problematic library which is compiled with a matching version of Xcode.