ARCHS[@]: unbound variable in Xcode 12

Note :- React native developersAfter wasting couple of hours only solution that worked for me was

Open VSCode and go to directory ios/App/App.xcodeproj/project.pbxproj that fileand perform a search EXCLUDED_ARCHS

EXCLUDED_ARCHS = arm64;

and delete everyline containing EXCLUDED_ARCHS

ios swift xcode12

You may try below steps:

In Main Project(Not TARGETS), Go to build settings and add Simulator-iOS 14.0 SDK with value arm64 inside Excluded Architecture and repeat the same for the Pod project too.
Delete VALID_ARCHS from your Main project and Pod project both.(You may open the project file in editor to delete this) [You already did this ✅ ]
Upgrade all Pods to the latest version available.

Last, Clean Project and Re-Build.

ios swift xcode12

For Xcode 12.3, when there is no VALID_ARCHS property, follow below steps:

Build Settings -> Build Active Architecture Only -> Debug -> Yes
Add "arm64" in "Excluded Architectures" in build settings of both project and pods project, to run the app in simulator. Remove it while making build on device or archiving the app.

CodeHunter