TestFlight error "Your request couldn't be completed"?

Question

I'm testing an iOS App using TestFlight. I have already successfully tested 8 Build pre-release but now it is not working anymore.
I have upload the built and it has been approved by Apple, invitations to external testers has been sent and properly received, but when they open TestFlight and try to download the App the download stops just before the end and an alertView says:

Your request couldn't be completed

NOTES: I have tried the download on different devices but none has worked.
TestFlight is incrementing installation count also if none download has been completed.
I have upload the built today in the morning.

Answer 1

Sometimes the error just happened when you just published your build on TestFlight and your tester clicked 'Update' in TestFlight right away. If this happens, what worked for me was just waiting for 5-10mins and just try again.

Answer 2

What worked for me was closing testflight and then opening again and installing.

Answer 3

What worked for me is putting the test user under interal testing then accepting the email invite saying to open testflight and I had no problems

ALSO make sure you do not have the app installed already through xcode

Answer 4

An external tester of us received the "Your Request couldn’t be completed. Try again." error when he received an invitation before the app was actually approved for external testing, due to an error at Apple's side.

After re-inviting the same user, the TestFlight build went to the "Waiting for Review" status, which eventually fixed the problem.

Answer 5

Found solution.

Latest XCode version changed the default build code signing identity to Developer, when it should be Distribution to work with TestFlight. While it throw any error while uploading, it's the one causing the problem.

Just change it and it will work again