Xcode 8.3.3 "No accounts with iTunes Connect access"
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.
I suspect that Apple has broken something with the IOS 11, etc upgrades going on. It was all working fine over the last few months, including yesterday, and suddenly today its broken.
As a temporary solution, I had to use export to local disk (from Archive), then select: XCode/Open Developer Tool/Application Loader.
Had the same stupid problem.Ultimately exported the .ipa to disk (via Xcode itself) and used altool command line tool to upload the ipa. It worked!!
altool --upload-app -f YourIpa.ipa -u <username>Apple should really spend some $$$ on improving Xcode and the overall Developer experience. Its painful.
I again went back to Xcode to try and upload but met with the same error, so command line was indeed helpful.