At that time we were struggling to transfer the application to another account when we got this error. I don’t know if we faced with some kind of bug but the problem was fixed when we deleted the identifiers in all accounts and added them again. I don’t know if this solution fit for you but you may consider this.

Here I tried to explain the problem more clearly. We have an iOS App with watch app and its extension. It's also available on the store. We developing a new version of this app. The problem that we faced is we accidentally deleted the bundle identifiers of WatchOS and WatchOSExtension from both Xcode side and AppStoreConnect "Identifiers" section. Scenario 1 - When we upload a new binary of new version (2.4.0 Prepare for Submission Version) with new bundle identifiers that we registered from App Store Connect, we get back a mail about "trying to change bundle identifier" naturally. For example: our 2.3.3 bundle identifiers also deleted identifiers are; "com.company.app.watchkitapp" and "com.company.app.watchkitapp.watchkitextension". When we use new registered identifiers (com.company.myapp.watchkitappp) mail comes like; "ITMS-90477: Invalid Bundle Identifier - Attempting to change bundle identifier from com.company.app.watchkitapp.watchkitapp to com.company.app.watchkitappp is disallowed for bundle My App.app/Watch/My App Watch.app." Scenario 2 - Yes we deleted our watch identifiers. So when we try to register these identifiers back again, it says; "An App ID with Identifier 'com.company.app.watchkitapp.watchkitapp' is not available. Please enter a different string." Any help is appreciated. Thx.

Same here in Turkey. :(