There was an error sending data to the itunes store "scheduling restart shortly"
Wait for while it automatically restarts this process and your app is uploaded.
I faced the same issue. I just wait in the same window.
Doesn't it means that there is a scheduled maintenance for iTunes Connect and that you should just try again later?
Faced this issue several times and many a time it was resolved automatically upon auto restart from the Xcode itself as they mentioned in the message scheduling restart shortly.
However, if the issue still persists there might be an issue with your internet connection, in my case issue was with the firewall and upon changing the firewall it was resolved. In such cases using your mobile data will help upload the build.