I have a rather curios issue and I'm not sure if it's hardware or software related. I have a PC with Windows 10 LTSC 2019 installed on it. Recently I tried to do an in-place upgrade to LTSC 2021. The installer proceeded without problems, but then after reboot and POST it simply failed. Upon loging in to Windows it showed the following error message: "The installation failed in the SAFE_OS phase with an error during BOOT operation". I've tried disabling various services, reinstalling drivers, doing a clean boot, etc. Nothing worked. Eventually, I gave up. I wasn't in the mood for a clean install. But this is where things got interesting. You see, I decided to boot from the flash drive on which I mounted the Windows ISO with Rufus. The moment I did so, the PC restarted, just as it did during the aforementioned upgrade attempt. And that is the problem. Every single time I try to boot from a USB drive - it doesn't matter which USB drive I use - the PC simply restarts as if I pressed the restart button. There are no error messages. There is one minor difference, however: if I convert the flash drive to MBR instead of GPT, it doesn't reboot instantly. It takes some time to load, but the moment the GUI is about to show up, it restarts. Besides Rufus I tried to use the official MCT and WinToUSB. Regardless of the program or the version of Windows, result is always the same. I've tried resetting the BIOS. The PC passes every stress test and as far as I can tell there is no issue. Everything simply works fine. The thing that worries me is that if by some chance my current Windows installation - which I installed without a problem a year ago - became corrupted I wouldn't be able to repair it. The one thing I didn't try is to boot into Linux installer or Live distro, but it wouldn't matter anyway, as I have to use Windows exclusively on this PC.
Have you try to D\L a clean image from here and try again, you mention the pc pass all stress test i assume that includes the HD because you mite have a bad HD.
I've got 2 SSDs (one used as a boot drive) and 1 HDD. They're all working without issues and none were detected.
Try booting Windows with another usb port to see if it works. I would try a linux distro to see it boots fine, if it does then it's probably a driver crash or corrupted file in windows bootup
@ OP If i understand right ? .......... You didnt make a full system / hard disk / partition back up before you started to do an inplace upgrade and it failed . .......... then you tryed several different solutuions ...... wich didnt work ? Each time you tried a solution wich failed did you put the system back into the state it was before you tryed your solution ........... before you tryed other solutions ? Now your system is messed up , and you dont know why ........... and you hope someone can tell you what happened ? ......... and sugest solutions ?
Another USB port doesn't seem to make a difference. Even if it does boot into Linux (I will check it out) that still doesn't solve the issue, as I need Windows on this PC.
If linux boots fine then it's not a usb hardware failure. Most likely the upgrade screwed something with your current configuration. Windows can get screwed up when doing upgrades or installing clean with multiple drives connected, I normally disable every other drive but the drive I'm installing Windows on so their are no issues. I would start by disabling all drives to see if it will let the Windows installer boot fine from usb.