I was trying to upload a pre-release build to iTunes to use it with the new iTunes TestFlight integration.
The way I have my continuous integration builds setup is that
Just a quick note, I faced this issue in archive when the SVN version number merge with the build version number. In my case I had 1.0(6771M) and the "M" which means SVN Modifications are there in the project, gave me an error when uploading the build.
So make sure you commit everything and prepare the archive.