When trying to upload an App to iTunes connect in Xcode 8.3.3, I get the error:
iTunes Connect access for "Team-Name" is required. Add an account in the Accounts preference plane.
The account already exists and (in some cases) has been working without incident previously.
How do I get around this issue with Xcode so that I can upload my app to the AppStore?
Had the same problem, First had to export the .ipa to disk using XCode and then upload to the AppStore with Application Loader tool.
It worked.