Having the same issue as well.

Any idea about this? am I doing something wrong or might it be an Xcode issue, @DTSEngineer?

I tried this approach after a meeting with an engineer (maybe it was you? :D) last week and sadly it doesn't work, same error appears. Here are some screenshots with the steps I followed: Added xcconfig files for Debug, Beta and Release configs and add a user-defined variable (in my case called BASE_BUNDLE_IDENTIFIER and PARENT_APP_BUNDLE_IDENTIFIER in the AppClip xcconfigs): And set these xcconfig files as the configuration files for each configuration of the target: Verify that BASE_BUNDLE_IDENTIFIER appears as set above the various build configurations under the user-defined section of the build settings pane of both your app and app clips: In the Build Settings pane of the target building your app, set the product bundle identifier (PRODUCT_BUNDLE_IDENTIFIER) setting to $(BASE_IDENTIFIER) for all of your configurations: In the Build Settings pane of the target building your App Clip, set the product bundle identifier (PRODUCT_BUNDLE_IDENTIFIER) setting to $(PARENT_APP_BUNDLE_IDENTIFIER).Clip for all of your configurations: In your App Clip's entitlement file, set the Parent Application Identifier entry under Parent Application Identifiers to $(AppIdentifierPrefix)$(PARENT_APP_BUNDLE_IDENTIFIER). There should only be an entry under Parent Application Identifiers. Also in the main target's entitlement make sure that the app associated appclip identifier matches the bundle identifier of the AppClip using the user-defined variable:

We've been trying to do the same for the last weeks and I find no way to properly configure it. In our case we have Beta and Release. Both configurations with different bundle identifiers: com.demo.app and com.demo.app.beta. I've tried to configure the project to use different entitlement files for both the app and the appClip. After a call with an Apple Engineer they told me the way we should use to trick Xcode is using xcconfig files and set user-defined variables to setup the bundle identifiers and to set the parent app bundle id in the entitlement files; and use only entitlement file per target. After configuring everything the same signing errors appear. I feel like it may be a bug in Xcode. A valid alternative for me would be to be able to configure Xcode to avoid assigning an appClip for the beta configuration, as dmrschmidt2 is pointing out but I think that would be even harder to accomplish.