1607 update fail - You can't install windows on a USB flash drive ....

I am running WIN 10 on a desktop PC and as of Monday I had all the current release updates installed (Not an insider on this PC)

Tuesday night I used the "check for updates" and walked away.

This AM I had an error message. I selected the "Fix issue" radio button and got an error message "windows 10 couldn't be installed. You can't install windows on a USB flash drive using setup"

I have NO USB flash devices installed, only a USB mouse/keyboard.

If that doesn't work, try this:
If using a PC, in Regedit HKEY LOCAL MACHINES/System/Control change 'Portable Operating System' from '1' to '0'.

I was referred here from another forum (Windows Secrets Lounge). After trying almost everything else and nearly giving up, I tried this fix with version 1607 - and it worked.

Thank you.

The solution worked for update to 1709 from 1607, too. Thanks!