If you tried to migrate to Xcode 8 and your build started to fail while you can build it locally, there's a great chance that this is caused by the code signing changes introduced in Xcode 8. Discovering the exact cause of the error involves checking the Xcode Archive step logs for more details about the error, which may include missing provisioning profiles or code signing issues. Xcode 8's automatic code signing feature works by first creating an archive signed with development code signing and then resigning it with distribution signing. This requires collecting all necessary certificates and provisioning profiles, which can be automated using the updated codesigndoc tool. Migrating to Automatic code signing involves upgrading steps in your Workflow, removing previous code signing input options, and setting up the export method for the Xcode Archive step. The updated codesigndoc tool helps collect required code signing files automatically, making it easier to use with Xcode 8 automatic code signing.