Application Loader: "Cannot proceed with delivery: an existing transporter instance is currently uploading this package"

Question

I have been unable to overcome this error in Application Loader. I've quit, restarted, tried different computers - it's like the server is hung up on an op that I never initiated and it won't time out. Has anyone seen it before and beaten it?

Answer 1

https://devforums.apple.com/message/282868#282868