Xcode 10 Error: Multiple commands produce for 'app' and 'appex'
In case someone is still struggling with this after updating cocoapods and reinstalling pods:
- Open Build Phases of the target which gives you problems
- Open Copy Pods Resources phase.
- Make sure the Output Files is empty. In my case I had a strange entry
${TARGET_BUILD_DIR}/${UNLOCALIZED_RESOURCES_FOLDER_PATH}
. I removed it and the build was successful
Solved my problem by updating Cocoapods from 1.4.0 to 1.5.3