Cordova build iOS error: archive not found at path 'path/to/myApp.xcarchive"

There is a work around here.

If you're building on the command-line, you can specify --buildFlag="-UseModernBuildSystem=0":

# Cordova CLI
cordova run ios --buildFlag='-UseModernBuildSystem=0'
cordova build ios --buildFlag='-UseModernBuildSystem=0'

# Ionic CLI
ionic cordova run ios -- --buildFlag="-UseModernBuildSystem=0"
ionic cordova build ios -- --buildFlag="-UseModernBuildSystem=0"

If you're building with a build.json config file, you can add the following under the iOS release or debug config:

"buildFlag": [
  "-UseModernBuildSystem=0"
]

If you are opening the project in the Xcode IDE, you need to change the build system in Workspace Settings to "Legacy Build System"

Neither solution - --buildFlag="-UseModernBuildSystem=0" or setting the Legacy Build System worked for me.

For some reason, the error only goes away if I am sure to unplug my iPad or iPhone from usb on my computer before running the cordova build command.

Maybe something quirky about my configuration, but I thought I'd share in case it helps anyone else.