After installation of KB4056892 boot failure, after roll-back error 0x800f0845

On the black screen, I can ctrl-alt-del and get to the menu where is displays task manager, log off, switch user, etc. but selecting task manager just takes me back to the black screen. I can switch users but each user just goes back to the black screen. What's even stranger yet, the only keyboard combination command that functions on the black screen is Win-P. Which shows the (4) monitor display options. Primary is selected and I cycled through the other (3) options with no different results. 

Have you tried starting Narrator to help with workarounds?   Win+Ctrl+Enter.  Do you have a second monitor to attach?   It sounds like your video driver is a problem.  You could use the Login screen's Power button's Shift-Restart command to get into the Advanced Boot Options to try using Low video resolution with a retry.  This would be an even simpler option if you had a boot menu to start from.

Good luck

Robert Aldwinckle

Egy tiszta ujratelepítést csináltam és megoldódott a probléma a bild szám nem stimmelt.

Thank you for the response. I was hoping to avoid this course of action but will keep it mind as a last resort.

Köszönöm a választ. Reméltem, hogy elkerülhetem ezt a cselekvési folyamatot, de végső megoldásként tartom szem előtt.

If you can get to a command prompt then you could run a scan to ensure you still have disk consistency. SFC /SCANNOW 

Tried this as well though I do not have any reason to suspect the file system being corrupt. When entering CMD Prompt (from the Win 10 recovery menu), it must create some sort of virtual drive. The initial default drive is X:\ and it doesn't allow me to change to any other root directory (actual Win 10 install directory is E:\ for whatever reason). Though I can still see the contents of other drives. And because of this, SFC reports it is unable to perform the task and exits.

I really wish there was a simple way to revert some of the updates to get this back to a working state. With no system restore points though, it's not looking good. I suppose the next option is a "PC Refresh" where I can maintain personal files but will need to re-install programs and such. Which could be beneficial as some unintended "house cleaning".

Have you tried starting Narrator to help with workarounds?   Win+Ctrl+Enter.  Do you have a second monitor to attach?   It sounds like your video driver is a problem.  You could use the Login screen's Power button's Shift-Restart command to get into the Advanced Boot Options to try using Low video resolution with a retry.  This would be an even simpler option if you had a boot menu to start from.

Good luck

Robert Aldwinckle

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Thanks for the reply and suggestions. I tried connecting a 2nd monitor and can switch between them using Win+P (very strange). As mentioned, I've since removed the video card and am only using on-board video at this point to hopefully simplify matters/drivers. I will try the low resolution option to see if that gets any better results.

EDIT: Tried low resolution mode and seems to be the same result (only larger mouse pointer in low-res). I'm going to try letting it run a bit as described below to see if anything different happens.

On a related note, since it "appears" to be booting into the respective user account (albeit a black screen), if I leave my LAN connected, and leave the PC for awhile, is there a chance it will run Win Updates in the background and the issue might self-correct? Wishful thinking I know, but who knows at this point.

 who knows at this point.

Please use Narrator to keep control even though you can't see what is going on anywhere.   I'm mystified about that.  I was hoping you would be able to see more with Low res.  Note that as soon as any Accessibility program is running you would have something to show in an Alt-Tab list.  So, it is surprising that you can't see either Task Manager or Narrator on the screen.   We can ignore the state of explorer.exe in that case (or then learn to start focusing on its problems and try to figure out how to work around them).

Another one that would change the video to be viewed is Mangifier in its Fullscreen mode with its Reversed video option.  OMG.  They have "modernized" that too?  I  just got Magnifier started conventionally with Win++, got into its Views menu and switched to FullScreen, and then tried to use its Tools menu but got taken to ms-settings:magnifier (or whatever it is--nothing obvious like that) which of course for you would require a completely functional explorer.exe.  

<voice actor="Dorothy" >  Toto, this isn't Kansas, is it?  </voice>