The yesterday released Intel microcode update that should protect Windows users against Spectre attacks, causes issues for some Windows 10 users. Users complain on Reddit, Twitter and the Microsoft Answers Forums. The affected update appears to be KB4100347.
Some users could no longer start their system or login to Windows after they installed the update. Mainly users with Xeon E5 and Haswell Core i5 processors seem to be affected. One user reports he found a workaround, but this method requires disabling Windows Update, because else the update is automatically installed again.
Besides that, there are reports from AMD users that they also received the update. That is strange, because it’s needless to say that AMD processors don’t benefit from Intel microcode updates.