Same problem here, filed as FB25297487 with a device log archive attached. Internal tester (the Account Holder) cannot install a new build that App Store Connect reports as VALID and IN_BETA_TESTING; TestFlight shows "The requested app is not available or doesn't exist." The device log shows why: TestFlight's POST to testflight.apple.com/v2/accounts/.../apps/<app id>/builds/<build id>/install returns HTTP 404 (X-Apple-Jingle-Correlation-Key AEAFHTKE5DYNZR3BOVNKCBXOZY, 2026-10-23 14:01:21 GMT). So the TestFlight server says the build does not exist while App Store Connect says it is ready. External beta review submission is also rejected: 422 BETA_CONTRACT_MISSING since 2026-10-18, and today a generic 422 "Please try again later". Agreements are active. Earlier builds expired days after upload. Recreating the app record under a new bundle ID did not help. To collect the device log without a sysdiagnose, connect the iPhone by cable and run pymobiledevice3 syslog collect --start-time <unix time before the install> out_dir, then search the TestFlight process for "host-install" and "code=404".

Same here; right after some new agreement; all of my apps expired suddenly before their expiration dates, and now I cannot test any apps on testflight as neither an internal or external tester.

Same here.

@DTS Engineer same here; "The requested app is not available or doesn't exist" not able to test as internal tester; or submit builds for external tests.