Check dependencies No architectures to compile for (ARCHS=i386, VALID_ARCHS=armv7 armv7s arm64).

Xcode builds a target for each CPU architecture listed in ARCHS, but limited to only architectures listed in VALID_ARCHS. That is, it builds only architectures that are in both lists. In your case, there are no architectures in both lists, hence the error. (I have no idea how that happened when you changed the project for a watchOS target.)

You will need to manually repair these build settings. In Xcode, you can select the project item in the navigator list, select the appropriate target in the target list, and choose the Build Settings tab. Both of these settings are in the first section of the settings editor.

Note that it's not clear from your post whether the messed-up settings are for the watchOS target, or for an existing iOS target, or both. You'll have to figure that out.

If you don't know what the correct settings are supposed to be, you can create a new project with a suitable target, and look at the default settings to see what you should change in your project.

If you can re-create the problem in a new project, then submit a bug report, too!

i386 is the simulator/your mac.

What are you building for when this happens? Store build for distribution (select generic device instead of sim in that case)? Testing to your device(s)?

What did that existing project originally support? Is it in the store now?

Which version Xcode?