DCDevice last_update_time issue

Question

Created 4d

Replies 1

Boosts 0

Participants 2

We are currently experiencing an unexpected issue with the DeviceCheck query_two_bits endpoint. According to the official documentation (Accessing and Modifying Per-Device Data), the last_update_time field should represent the month and year when the bits were last modified.

The Issue: For several specific device tokens, our server is receiving a last_update_time value that is set in the future.

Current Date: April 2026

Returned last_update_time: 2026-12 (December 2026)

Here is a response:

{
	"body": "{\"bit0\":false,\"bit1\":true,\"last_update_time\":\"2026-12\"}",
	"headers": {
		"Server": ["Apple"],
		"Date": ["Thu, 02 Apr 2026 06:05:23 GMT"],
		"Content-Type": ["application/json; charset=UTF-8"],
		"Transfer-Encoding": ["chunked"],
		"Connection": ["keep-alive"],
		"X-Apple-Request-UUID": ["53e16c38-d9f7-4d58-a354-ce07a4eaa35b"],
		"X-Responding-Instance": ["af-bit-store-56b5b6b478-k8hnh"],
		"Strict-Transport-Security": ["max-age=31536000; includeSubdomains"],
		"X-Frame-Options": ["SAMEORIGIN"],
		"X-Content-Type-Options": ["nosniff"],
		"X-XSS-Protection": ["1; mode=block"]
	},
	"statusCode": "OK",
	"statusCodeValue": 200
}

Technical Details:

Endpoint: https://api.development.devicecheck.apple.com/v1/query_two_bits (also occurring in Production)

Response Body Example:

JSON

{
  "bit0": true,
  "bit1": false,
  "last_update_time": "2026-12"
}

Observations: This occurs even when our server has not sent an update_two_bits request for that specific device in the current month.

Questions:

Is there a known issue with the timestamp synchronization or regional database propagation for DeviceCheck?

Does the last_update_time field ever represent an expiration date or any value other than the "last modified" month?

Best regards,

Boost

Answer 1

Engineer OP

Apple

3h

We believe this might be a bug in DeviceCheck for an edge case you seem to be running into, and the team would appreciate a Bug Report for this in order to investigate the cause and issue a fix or suggest a workaround.

We would also require a diagnostic log from the device to see if this is indeed a bug or a device side anomaly. If you can please run your app and/or take the actions for the device to record a last_update_time, and once that is done create a sysdiagnose following these instructions. If the problem devices are only in the hands of your users, then please send as much details and logs from your server side communications. If you are able to provide it, the first time stamp for when update_two_bits was sent for this device and wrong last_update_time returned by the last query_two_bits would be essential information.

Once you have created the bug report and added the relevant information, please share the Feedback ID here, and @mention me in your reply so I can pass on the information to the DeviceCheck team right away.

1