Just finished installing W10 and everything appears fine, except my second monitor no longer works.  Windows 10 say it cannot detect a second monitor.  Worked fine in W8.1

I have this problem on my Surface as well. Worked fine with W8.1, now it does not detect the other monitor via Settings> Display dialog. Have also tried Project to a Second screen via W10 search bar and get this helpful suggestion: “PC can’t project to another screen. Try installing another driver”