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After trying to remove Zorin OS from a dual boot machine (Win10, Zorin), W10 cannot boot anymore and goes directly to a BIOS memory scan.

This machine has Windows 10 Pro, version installed this year with its updates. Can I fix MBR using a different installation media of W10 than the installed right now?,

for example W10 home, W10 pro 2020 version, W10 2020 in other language.

Those are the only disks burned on DVD I have available now, since don't have easy access to another Windows 10 machine. Thanks in advance

Update

In boot options have this

UEFI boot options

When I enter in Windows boot manager, runs a memory scan and when finishes appears this enter image description here

Ger Cas
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  • Yes, probably. But the main question is why are you using Legacy installations (and MBR)? UEFI mode has been "mandatory" for any preinstalled Windows 8 or newer since 10 years ago! With UEFI mode (and GPT) this kind of problems do not exist. – ChanganAuto Aug 11 '22 at 17:06
  • Actually when boot, windows, Ubuntu UOS, appears under UEFI boot options. I think that means is in UEFI mode right? – Ger Cas Aug 11 '22 at 17:33
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    If it is then you must have GPT, not MBR, and the "fix" you're trying to do isn't applicable and is unneeded, just a relic of the past. With UEFI mode, in this situation, ALL you need to do is to open UEFI settings > Boot and change the boot order to "Windows bootloader manager", end of story. EFI entries for the now deleted OS remain but it makes no difference whatsoever and you can run tools for that later from Windows. – ChanganAuto Aug 11 '22 at 17:40
  • Actually under UEFI boot options, Windows 10 is the first one. Zorin partition still is not removed, but even though, cannot boot in windows directly – Ger Cas Aug 11 '22 at 18:11
  • If you can't boot Windows directly you can't via Grub either. Unless... You modified the Windows entry somehow. Years ago it was a suggested workaround for those rare laptops with "broken" UEFI that only booted Windows regardless of user selections in boot order. – ChanganAuto Aug 11 '22 at 19:39

2 Answers2

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If you're seeing UEFI boot, then your disk is probably in GPT format, not MBR. In addition, you might have damaged the EFI partition while removing Zorin OS.

I suggest to use exactly the same Windows boot media as that of the installed Windows, to do the following:

  1. Run a Startup Repair, and if it didn't help,
  2. Repair Install of Windows 10 with an In-place Upgrade.

It is important that the second method should find your Windows 10 partition on the disk. If the partition isn't found, then it also was too damaged to be recognizable.

In this case, your Windows setup is gone - you should do a clean install of Windows. If you need to save some data from the Windows partition, use a Linux Live USB to do that.

In the case of a clean install, it's safer to just format the disk and install Windows to the Unallocated area (which should be the entire disk).

harrymc
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  • I think Windows partition is fine, since if I run a Linux live USB, I can access windows folders and files. I updated my original question with a photo of how I see the boot options. The "exactly windows media" would be only W10 pro, nor matter sub versions? – Ger Cas Aug 11 '22 at 18:22
  • Yes, but does choosing Windows Boot Manager work? – harrymc Aug 11 '22 at 18:23
  • When I enter in "Windows boot manager", begins a memory scan of Dell support assist and when scan finishes, only gives option of shutdown. . When you say use the "exact windows boot media" would work if I download latest W10 pro iso? Since I don't know which sub version the system has. – Ger Cas Aug 11 '22 at 18:27
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    If Pro is installed, use the Pro boot media. If you can download the latest media, this will save some time afterward, but if this is too difficult then use the one you have. – harrymc Aug 11 '22 at 18:30
  • I'll try to download the latest then. I've uploaded the photo of what appears after select windows boot manager and memory scan if matters. Thanks – Ger Cas Aug 11 '22 at 18:37
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    "No bootable devices were found" - your disk is missing the startup code, but Windows may still be intact. There is a chance that Startup Repair will help. – harrymc Aug 11 '22 at 19:08
  • I've tried option 1 and didn't work. Then I tried `bootrec /fixmbr... fixboot, export bcd` and other steps since in the process, windows installations found were 0. Then exported bcd, renamed to bcd.old, bootrec /rebuildbcd and few other things make the trick. Thanks for your help – Ger Cas Aug 12 '22 at 07:27
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The MBR installed by Windows has one main task: find the 'active' partition and jump to its VBR. This doesn't depend on the OS language nor license.

(It shouldn't depend much on the version either – AFAIK, all Windows versions since Vista have use same MBR contents, but you could probably get it working even with a Syslinux mbr.bin, or a Win98 MBR or a MS-DOS MBR. It's only the GRUB MBR that's a bit of an outlier here.)

The system partition's VBR does a bit more (it has to actually find the BOOTMGR file in NTFS), but that also works the same way across all Windows license levels.

u1686_grawity
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  • Great answer +1 but probably not applicable. OP seems confused and may actually have UEFI mode and GPT (strictly required for Windows), so the likes of "fixmbr" aren't applicable and no need for booting installation media at all. – ChanganAuto Aug 11 '22 at 17:43
  • No, as you've said yourself UEFI mode has been "mandatory" for **preinstalled** Windows – there is no such requirement for manual installations done from regular installation media. (At least not in Windows 8/8.1/10.) If it had been mandatory, Microsoft wouldn't have been shipping MBR/BIOS support in tools like 'bcdboot'. – u1686_grawity Aug 11 '22 at 17:46
  • Correct but I'm only going by the OP's comment (after your answer): *"windows, Ubuntu UOS, appears under UEFI boot options"*... And indeed if installed the the user any Windows version from 7 (with tweaks) up to 10 can be installed either way. Windows 11 finally ditched the Legacy/"BIOS" mode. – ChanganAuto Aug 11 '22 at 17:57
  • I tried `bootrec /fixmbr... fixboot, export bcd` and other steps since in the process, windows installations found were 0. Then exported bcd, renamed to bcd.old, bootrec /rebuildbcd and few other things make the trick. Thanks for your help – Ger Cas Aug 12 '22 at 07:29
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    `The MBR installed by Windows has one main task: find the 'active' partition and jump to its VBR... It shouldn't depend much on the version either` this is completely wrong!!! [bootsect has `/nt52` for WinXP or older, or `/nt60` or Vista and newer](https://docs.microsoft.com/en-us/windows-hardware/manufacture/desktop/bootsect-command-line-options?view=windows-11) and /mbr to to install the MBR instead of VBR. The NT60 bootloader is vastly better and can even boot from a logical partition instead of only the active primary partition like NT52 – phuclv Aug 12 '22 at 16:57