TestFlight: “Could not install. The requested app is not available or doesn’t exist.” (internal testers, incl. account holder) + external testing fails – Case ID 103006602341

Hello,

My app uploads and processes successfully in App Store Connect, but nobody can install it from TestFlight, including me as the account holder. Tapping Install/Update fails with:

“Could not install [App Name]. The requested app is not available or doesn’t exist.”

Trying to add the build to external testing also fails with a message saying a technical issue occurred and to try again later.