MacBook-iPhone Sync via USB does not work: "AMPLibraryAgent PrepareToLoadDatabases() failed!" Since I updated my iPhone 7 to iOS 13.4.1 the Sync with my MacBook (Mid2012, macOS 10.15.4) does not work anymore.
When connecting the iPhone and selecting it in the Finder, it first says "Loading", but then it says "There was an error communicating with an utility programm" (German: Die Kommunikation mit einem Hilfsprogramm ist fehlgeschlagen) and below is the loading wheel and it stays that way forever.

When looking into the console, it seems like the program is the following part:

fehler    19:05:32.710148+0200    AMPLibraryAgent    **ERROR**: PrepareToLoadDatabases() failed! status:7011
fehler    19:05:32.710781+0200    AMPDevicesAgent    **ERROR**: getDomainInfo: failed! error:Error Domain=NSOSStatusErrorDomain Code=7011
standard    19:05:32.710892+0200    AMPDevicesAgent    amplc&gt; get library domain info complete. status:7011
fehler    19:05:32.710932+0200    AMPDevicesAgent    Assertion failure: err == (7011)
fehler    19:05:32.710963+0200    AMPDevicesAgent    Assertion failure: err == (7011)
fehler    19:05:32.710990+0200    AMPDevicesAgent    Assertion failure: err == (7011)
fehler    19:05:32.711137+0200    AMPDevicesAgent    Assert failure: ("false")
fehler    19:05:32.711313+0200    AMPDevicesAgent    Failed to initialize full service: 7011
standard    19:05:32.712003+0200    AMPDevicesAgent    SCNetworkReachabilityCreateWithName callback: Flags = 2 (net is UP)


When logging into another user on the same computer, the iPhone is recognized and I could hypotheically sync it, but of course, the other user doesnt have my Photos, Music etc... and even if I copy everything I assume the error might persist because there seems like there is one library/database in my user folder which cannot be loaded and causes the error.

It looks like some Database cannot be loaded by the AMPLibraryAgent, but it does not say which one. Does anyone know how to find out which database/library it is in particular?
I found the problem:
I havent had opened the App TV yet and therefore that database was missing and thus AMPLibraryAgent would get this error...