"The app couldn't be installed because Testflight isn't available"

We are unable to install a number of our apps on testflight due to this message:
"The app couldn't be installed because Testflight isn't available"

Of 5 apps we can install 2 of them.

Of the 3 that do not work, none of the previous builds will install either.

Does anyone know the cause of this?

We were able to download and install builds yesterday.
Answered by gollumullog in 671672022
I believe I found the cause/solution at least for my problem:
On Apr 17th our code signing certificate expired:

```

00:21:45 error: No certificate for team '...' matching 'Apple Distribution: ... (...)' found: Select a different signing certificate for CODE_SIGN_IDENTITY, a team that matches your selected certificate, or switch to automatic provisioning. (in target 'Unity-iPhone' from project 'Unity-iPhone')
00:21:45 error: Provisioning profile "..." expired on Apr 17, 2021. (in target 'Unity-iPhone' from project 'Unity-iPhone')
```
All builds built before this time will not install in TestFlight, all builds after do install.

Solution:
Built a new build and it installs fine. This caused a number of issues with testing, as we can no longer test old builds, but solved our immediate issue.

We have the same Problem, you're not alone !

I tried to uninstall and install again, restart phone, it didn't work ^^
Accepted Answer
I believe I found the cause/solution at least for my problem:
On Apr 17th our code signing certificate expired:

```

00:21:45 error: No certificate for team '...' matching 'Apple Distribution: ... (...)' found: Select a different signing certificate for CODE_SIGN_IDENTITY, a team that matches your selected certificate, or switch to automatic provisioning. (in target 'Unity-iPhone' from project 'Unity-iPhone')
00:21:45 error: Provisioning profile "..." expired on Apr 17, 2021. (in target 'Unity-iPhone' from project 'Unity-iPhone')
```
All builds built before this time will not install in TestFlight, all builds after do install.

Solution:
Built a new build and it installs fine. This caused a number of issues with testing, as we can no longer test old builds, but solved our immediate issue.

Having the same issue right now with Facebook app and messenger.
It cleared up whatever was causing it.
"The app couldn't be installed because Testflight isn't available"
 
 
Q