An internal user who could install and test a couple of early versions of my app, can't install the new version on her device. I didn't change certificates/profiles in the new version. This is her experience with the new version:
The download has been unsuccessful, so I cannot try the current version of the app. It shows the update in Test Flight (version 1.3.2 (6)), and shows it downloading, but then I get an error message that says "Unable to Download App: myApp".
What can be the cause of this problem?
This kind of problem occurs because of the size of your IPA file. I faced the same issue.
If it is above 50mb then try to download it through your WI-fi not from your mobile connection.
For best practices, we should always download an IPA file through wifi to avoid this kind of issues.
It helped me.
Hope it works for someone else also.