Windows 10’s problems are growing. Despite the introduction of new monthly charges, the number of high profile incidents with recent updates (including one which deletes users’ personal data) is off the charts. And now Microsoft has warned there is another serious problem...

Spotted by The Register, Microsoft’s activation servers have started accidentally downgrading expensive Windows 10 Pro systems into cheaper Windows 10 Home PCs, then invalidating their licences. Needless to say, that's a nasty financial hit (Home is $119, Pro is $199) and affected users are furious.

“After updating to Insider Build 18277 my Windows 10 digital license became invalid. I don't understand!...No hardware changes, nothing has changed. I don't know what to do,” tweeted one affected user.

“One of our three-year-old Lenovo Yogas just decided to throw 0xC004C003 Windows activation error. Windows diagnostic tool says the machine has Windows 10 Home license...Dumbasses” tweeted another.

And it’s not just upgraders being affected. Problems with automated Windows 10 Home downgrades are being reported with fresh installs on different Windows Pro versions as well.

“Same issue on Dell computers running Windows 10 Pro 1803 that we just bought. Need to deploy to clients but they won't activate,” explained another user on Reddit.

On its official Answers page, Microsoft warns there is a “temporary issue” with the company’s activation server but has not disclosed any further details. As for users calling Microsoft’s call centres, the response is to simply wait for a fix.

Forbes