@phwe said in Bookmarks gone after windows 10 update:

Peter (my old account) and Peter.Peter-pc (the new user).

The update/windows detected an issue (corruption and or access) with your account, so it created a new one so you can still access your computer. Obviously the old user account wasn't that bad as you were still using it, but something was up with it. Windows can do that on its own without an update too.

Wouldn't hurt to check your drive and chkdsk /r in an administrator command prompt (and restart) for good measure.