I downloaded Xcode 7.1 from the App Store today after working from 7.1 beta downloads from developer.apple.com and have a new iOS app build to upload. So I did:
Theres a few solutions I have come across to solve this issue.
Most common being to remove and re-add your developer account. This won't work on its own though, you need to also 'view details' on your account and have Xcode download your provisioning profiles again.
The other alternative is to upload your build using application loader. The disadvantage to using this solution is that should you be trying to upload using a beta build of Xcode or OSX you won't be able to change your apps .plist in the archive folder to trick iTunes connect into accepting it. In this instance all you have access to is your ipa.