CloudKit errors "Bad Container" (5/1014); "Couldn't get container configuration from the server for container "iCloud.com.abc.def"">

Is that the bundle ID of your application? Xcode creates a container on the server with the bundle ID of the current application. Double-check your application's bundle ID then follow the instructions in the CloudKit Quick Start to set up that container.

Please make sure that you've initialised the container properly. You can double-check with iCloud Dashboard if it has your container in the containers list.

The container is initialised with CKContainer.defaultContainer() call or a more specific CKContainer(identifier: String) initialiser. Bear in mind that CloudKit container ID is usually in the form iCloud.<bundleID>, where <bundleID> is the bundle ID of your app. So the root of the problem might be that you tried to share a container between different apps but forgot to add iCloud. prefix.