When I try to select the new version for Internal testing in iTunesConnect. It shows me an error "Operation_failed". But there is no reason why this error happens?
In the the version selecting dialog box, there is an warning message "Your latest build is still in processing". From this warning message, I can understand that, the latest build is still in processing state, but when I check in the Activity screen, (processing) indication is not displaying.
I also checked this issue for couple of hours, I have found the link https://forums.developer.apple.com/thread/23943?tstart=0, but in this link I didn't get any solution.
Same problem here, but you can use Application Loader to upload your app. This helped me with "operation_failed" error.