Sihost.exe - Unknown Hard Error, Nothing Helps

Nov 14, 2018
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Hello! I always make extensive efforts to search the web and so forth in order to fix my own problems, since I'm pretty adept with Windows. But I've spent the last two weeks trying everything I can find, yet nothing helps (the overwhelming majority of the sites I've checked are near duplicates, right down to the syntax and other errors. But to be fair, I've submitted this post elsewhere.)

Here's the situation: I have one SSD containing the system I'm using right now, which works quite well. But I want to copy this system partition to another SSD, more specifically a pair of identical SSDs setup in a RAID 0 configuration (Intel soft RAID). That RAID configuration has worked perfectly for several years. However, when I make any kind of clone, but the most appropriate type (IMHO) of clone for an OS partition is a byte-for-byte copy (although I've tried other types with the same result). I've tried cloning with the following applications: DiskGenius Pro, Acronis Disk Director 12.5, EaseUS Partition Master Pro v16.0, and AOMEI Partition Assistant Pro. All cloning operations work properly, with no error messages. A visual inspection of the clone seems fine, and I can run all the applications off the clone that I've tried.


When I try to boot from the new clone, the Windows 10 bootloader correctly allows me to choose to boot the clone (and the BCD is entirely correct), then I correctly see the rotating circles both before and after the BIOS page, then the logon screen correctly shows up, whereupon I enter my password, which is accepted.

Then I see a very bright, mostly white screen (it looks like a photo negative of the normal screen) with a dialog box in the center with the title bar reading: "sihost.exe - System Warning", with the actual message reading: "Unknown Hard Error". Thereupon the screen flashes roughly every second and the logon fails. But if I press CTRL-ALT-DEL, it correctly brings up the task manager, and there I see all the correct startup tasks. But that's all I ever see from then on.

I have the advantage that I can boot from the single, working SSD and easily work on the system volume on the RAID disks. Thus I don't have to boot from the repair or installation disk(s), although I've tried that too and run startup repair and double-checked the BCD and other such procedures. I've run CHKDSK both from the working online system as well as during boot up.

I've also tried running DISM offline repairs and offline SFC, but none of the sites which claim to provide instructions for those procedures are correct; they always produce syntax errors or the like, and as I said, nearly all of those sites are just plagiarized from each other (with minor variations) so I can't perform DISM or SFC according to their instructions.

Therefore, I've turned to the posters here. Can any of you offer help, please? Even the correct instructions and command lines for offline DISM and SFC would be a tremendous help.


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