Since 2 days I cannot install apps from Firebase App Distribution any more. The flow worked before and nothing has changed in the iOS signing process. This can be proved by trying to load and install old builds which previously worked on all phones. On all iOS devices (independently of the OS version) now the same error shows up:
Unable to install "app" This app cannot be installed because its integrity could not be verified.
I already reinstalled the firebase profile. This is also not the problem. The problem occurs suddenly on all devices so either Firestore app distribution for ios stopped working or a configuration change in the backend caused the issue.
Any idea or anyone having the same problem?
Ok, the problem is that my developer certificate has expired. I created a new one and it seems to work again. Thanks for the hint @Paulw11
And by the way, it wasn't marked as expired until I opened the details in the developer portal. But the date clearly was before now.