When trying to test my app on my device iPhone, I get the following error, I think it\'s something about registering my device.
/Library/Frameworks/Mo
The answer of Mephisztoe worked for me, except that I am working on Windows and you find the scheme-property in the project-settings and not in the plist-file.
Furthermore be sure that you installed fastlane (just open Extras > Options > Xamarin > Apple-Accounts and click on "install fastlane") and added your Apple-ID there.
I also deleted the certificate with the keychain-utility. That's why I had to reenter my password on the mac as I clicked on build on my windows machine.
With these steps done I can finally work again...