Activation lost after a Windows update?

Updates sometimes reset licensing data. Recovery takes minutes.

Three possible causes

• The update changed the edition or licensing channel. Check with slmgr /dli.
• The local KMS renewal task was removed during cleanup.
• An antivirus quarantined the KMS service during the update's reboot.

Recover in order

1. Run slmgr /xpr to read the state.
2. If a license is still shown but flagged, restart the Software Protection service.
3. Otherwise simply activate again as administrator with protection paused.
4. Confirm on the next reboot that activation persists.

Repeatedly losing activation after each update means something is removing the renewal mechanism, not an unstable license.

Check whether the repair is permanent

After reactivating, restart once more and run slmgr /xpr again. If it stays activated, the licence and renewal service are in place. If it reverts with no new update installed, something is actively deleting the local KMS component: scheduled optimizer tasks, a second antivirus, or a work policy.

Feature updates versus cumulative updates

Monthly cumulative updates rarely touch the licence. The yearly feature updates are the ones that rebuild activation data or switch channels when setup detects an inconsistent configuration. Deactivation on the same day every month is not the updates; it is the renewal timer being lost.

Before opening a support thread

• Save the output of slmgr /dlv as soon as the problem appears.
• Note the update KB number in Windows Update history.
• Check Protection history for anything quarantined during the reboot.

Those three facts usually identify the cause in minutes instead of repeated reinstalls.

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