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FAQ

Last Updated: Aug 09, 2021

This topic describes FAQs about UTDID on Android.

Under what circumstances does the value of UTDID remain unchanged and under what circumstances does it not?

Answer:

  • After the mobile phone or application is restarted
Without permissions on the SD card With permissions on the SD card
The value of UTDID Unchanged Unchanged
  • After the application is deleted and reinstalled
Without permissions on the SD card With permissions on the SD card
The value of UTDID Changed Unchanged
  • After you wipe the data and cache on your device, clear the data in the SD card, and then reinstall the application
Without permissions on the SD card With permissions on the SD card
The value of UTDID Changed Changed

Why is UTDID changed after I terminate a process?

Cause analysis:

  1. UTDID is the ID of an application on a device. Every time when the application is started, the UTDID outside the application is compared against the UTDID inside the application. The UTDID that was generated at an earlier time is used.
  2. When the application is installed for the first time, the application cannot obtain the outside UTDID because the application is not authorized to access external storage. In addition, the application does not have an inside UTDID. Therefore, the application generates a UTDID.
  3. After you authorize the application to access external storage and restart the application, the UTDID outside the application overwrites the UTDID inside the application. Therefore, the UTDID is changed.

Solution:

  1. Make sure that the version of utdid4all is not earlier than V1.1.5.3. A version earlier than V1.1.5.3 is incompatible with advanced versions of Android.
  2. This problem occurs only when you install the application for the first time. After you authorize the application to access external storage, the UTDID is not changed when you restart the application.
Note: For Android 6.0 and later, you cannot authorize an application to access external storage only by declaration. When you authorize the application on a specific device model, the authorization page may appear and you must confirm the authorization.

How do I ensure that the ID of a device remains unchanged in Android 10 and later?

As device authorization policies are more and more strict, the UTDID is difficult to remain unchanged on a device. If you need a fixed device ID in specific scenarios, use another way to specify the device ID.