iTunes Connect: Can't save app information after uploading new binary
For me, I was filling out the form in Safari and getting the error. I logged out, then switched to Chrome and signed in. This fixed the error, and I was able to submit.
I solved this by increasing the number in Build (Select the Target, then Xcode -> General -> Build, see picture) by adding .1 so the build was 3.75 -> 3.75.1. But only for the Build, the Version is still 3.75 and also appears like that in iTunesConnect.
Then the new binary uploaded and I could select it for review. In the picture below you may see the old and the new binary listed in iTunesConnect. Then I finally just had to select the new binary and submit for review.