Hello Thunkers,
You may have experienced some iOS build server error messages today. Please wait to try to publish until further notice. The engineering team is upgrading the build server.
[Update]
The engineering team was engaged in some routine maintenance and upgrading for the build servers. Sorry for any disruptions this may have caused users.
At this time 10:09 AM EST, the build servers should be live again for all users. If you are still seeing the error above, please wait a minute or two then refresh your browser and try again.