A phone or tablet problem starting right after an OS update, a new case/accessory or a restored backup should be checked against that change first. For iPhone App Store download and update, first try a free known-compatible app and inspect the exact download message.
What this covers
- iPhone App Store download and update with this exact failure state
- Diagnosis across one app versus account billing, storage, region, network and OS compatibility
What it does not cover
Try in this order
0 of 4 completedCapture the exact failure state
ReversibleNote the exact update version, accessory or backup date, and confirm the feature worked immediately before it. Expected behavior: authorize the correct account and install a compatible app with enough space.
Isolate the component boundary
ReversibleTry a free known-compatible app and inspect the exact download message. Test with the new accessory removed, or check the update's known-issues note for the exact symptom. Boundary to separate: one app versus account billing, storage, region, network and OS compatibility.
Correct only the proven cause
ReversibleCorrect account terms/payment, free space or update iOS before retrying. Reset the one setting the update changed, or replace the incompatible accessory.
Verify and stop safely
ReversibleConfirm normal operation with the change present for one full day of typical use. Do not remove the only authenticator or banking app without recovery access.
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