Some Windows 7 admins recently started their days with a rude awakening. They arrived to find that many, in some cases thousands, of PCs were no longer activated. Quick sleuthing determined the problem was recent Windows updates, KB4480870 and KB4480960.
Thousands of Volume Licensed Machines Were Deactivated
As detailed by Mary Jo Foley and Günter Born, a Windows 7 admin arrived to find that thousands of machines had been deactivated and were displaying a “not genuine” error message. The problem appears to have started after installing KB971033 in a monthly roll-up.
These particular machines are KMS activated, a volume licensing option offered by Microsoft. KMS activation allows an admin to activate many PCs conveniently by having them check in with a local server for a valid volume license key.
After installing the update, a problem occurred when a Windows 7 PC checked into the KMS server. The server sent a blacklisted error instead of the usual response, and this resulted in a “not genuine” message. As pointed out by Born, KB971033 is designed to validate standard Windows licenses and likely never should have made it to KMS PCs in the first place.