-Don't know what number update this was that I automatically received yesterday, but it left my current configuration unbootable, so that even my Macrium Reflect "Fix Boot Errors" could not fix it . . .
-Ran my last Full Backup from Reflect's Rescue disk, mid-August, and I am up and running again.
-Anyone else?
OK, have just read in another thread that 'Fast-Startup' may have a bug that may cause a problem with updates, so I have disabled that function and will report back if that seems to fix my boot problem after updating . . .
I had the same problem several times. And like you, I too had a Reflect disk backup that got me up and running in almost no time. After trying several different things I went to the trouble of downloading the Win10 ISO file, burning it to an optical disk, and running the update from there.
That failed also, but in a different way: After all the intermediate installs & reboots the update process says "We are restoring your previous system" which it does A-OK. But it leaves several directories of update stuff that have to be manually deleted.
OK, finally achieved Cumulative Update for Windows 10 Version 1607 for x64-based Systems (KB3176938) . . .
-System still did not boot-up after the update was applied; had to use my Macrium Reflect disk's "Fix Boot Problems" tool . . . That got me running again, so I must assume that turning off the Win10 "Fast Startup" feature does have something to do with at least this particular update causing boot problems . . .
-This update did once again 'un-mark' the drive letter on my 'D:-Data' drive . . . easy to fix but a nuisance to have to attend, again.
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