App Attest – DCAppAttestService.isSupported == false on some devices (~0.23%)

Question

Created Sep ’25

Replies 3

Boosts 0

Participants 3

Hi Apple team,

For our iPhone app (App Store build), a small subset of devices report DCAppAttestService.isSupported == false, preventing App Attest from being enabled.

Approx. impact: 0.23% (352/153,791)

iOS observed: Broadly 15.x–18.7 (also saw a few anomalous entries ios/26.0, likely client logging noise)

Device models: Multiple generations (iPhone8–iPhone17); a few iPad7 entries present although the app targets iPhone

Questions

In iPhone main app context, what conditions can make isSupported return false on iOS 14+?

Are there known device/iOS cases where temporary false can occur (SEP/TrustChain related)? Any recommended remediation (e.g., DFU restore)?

Could you share logging guidance (Console.app subsystem/keywords) to investigate such cases?

What fallback policy do you recommend when isSupported == false (e.g., SE-backed signature + DeviceCheck + risk rules), and any limitations?

We can provide sysdiagnose/Console logs and more case details upon request.

Thank you,

—

Answer 1

Engineer OP

Apple

Sep ’25

Is this happening intermittently on devices, or are certain devices stuck in this state forever?

If stuck in this state, have you tried:

restarting the device
deleting and reinstalling your app

If we needed to look at some logs, do you have any stuck devices in hand, or are these all customer devices?

Argun Tekant /  WWDR Engineering / Core Technologies

Answer 2

endecotp OP

Sep ’25

Is this actually Mac OS, with the app running in "made for iPad" mode?

Edited to add:

What fallback policy do you recommend

I recommend not using App Attest, precisely because for some small 0.xy% of users it doesn't work, and those are not all hackers.

Answer 3

Peerapon OP

Oct ’25

@Engineer

Hi Argun,

Thanks for the follow-up.

Behavior: On affected devices, DCAppAttestService.isSupported appears to be stuck false permanently (not intermittent). Current impact is small (~0.23%), but persistent for those users.

Tried: We haven’t yet asked users to restart or delete & reinstall the app. We will do that next and report back.

Devices: All affected devices are customer devices; we don’t have any of them on hand.

Could you advise what remote logs would be most useful for you? For example:

specific Console.app subsystems/keywords to capture (e.g., com.apple.devicecheck, DCAppAttestService), and

whether a sysdiagnose from an affected device would help (and which components to focus on).

If there are any known system/SEP conditions that can keep isSupported false until a DFU restore, please let us know so we can guide users appropriately.

Happy to provide any additional app details you need (Bundle ID / Team ID / build type). Thanks again.