Can’t boot after GPT conversion

Skyace888

New Member
Tried to convert my boot Win10 volume from MBR to GPT and can’t boot anymore. Set TPM and secure boot options. Ran the automated repair from this app on USB drive. Stuck in boot loop now. Data shows on drive though with bootable CMD prompt. How can I get it booting again?

Thanks!
-Al
 
To solve this problem, you need to convert MBR to GPT disk or enable Legacy boot mode in BIOS. By the way, you can use a freeware AOMEI Partition Assistant to convert disk between MBR and GPT without data loss.
My Pasco Connect
 

MicroSuck

Member
I tried converting between MBR and GPT, and although the conversion works, windows won't go for it. For starters, the MBR bootstrap uses BOOTMGR and keeps it's BCD in the BOOT folder. The GPT bootstrap keeps it's BCD in EFI, someplace. I tried adding all the files for both to the system, but still, it's one or the other, period. And no conversion, it wouldn't boot at all after that, either way. I have gotten a partition that showed up in my bios as both an EFI partition, and an MBR partition, but only one will boot. I can make either one boot, depending on which way windows is installed, but never both. So converting is useless, if you do that, it won't boot anymore.
If it means that much to you, what I would do if I HAD to get that system to work, I'd use DISM (or Gimagex) to capture the working system as a .wim image, and format the partition with Rufus, which will reinstall the wim you made of your system at the same time. And that wim image is 10x better than any system restore point. That's what I had to do, but that actually worked. Rufus is usually used to install a brand new system image from the windows dvd, either the whole iso image, or sorces\install.wim. But it worked just fine with the image I captured of my existing, installed and working system, but you can only install back to the same partition it was captured from. The wim image of an 18gb installed system was just a bit over 5gb.
If you want to, pm me, and I'll link you to the software you need, and how to use it.
 
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Schulists

New Member
To solve this problem, you need to convert MBR to GPT disk or enable Legacy boot mode in BIOS. By the way, you can use a freeware AOMEI Partition Assistant to convert disk between MBR and GPT without data loss.
 

MicroSuck

Member
The only way I can think to make it work is first copy the "boot" folder, and bootmgr from either the windows dvd, or another MBR system, then replace boot/bcd with the one found in EFS:\EFI\Microsoft\boot on the EFI system. I haven't tried it, yet, but I'll get a chance pretty soon.
 

MicroSuck

Member
Boy, it wasn't easy, but I did it! And the best part is that it's working on a really old machine that windows 10 won't install on. My laptop died, and I used it's hard drive to get my old one out of retirement, as a backup until I have time to shop around for a more suitable replacement, This old one doesn't support EFI at all. But I had to abandon the EFI boot partition, for some reason. I put the boot folder in the primary user partition, and I made a new BCD store with EsyBCD, and made that the active partition. The other thing I did was make sure the partition had the right bootcode on it by running bootsect from the command line. But I was determined, since the first thing I did to get going was use EasyBCD to boot the windows 10 drive connected by way of the USB port, from the original HDD's BCD (as well as windows 11 I have installed on my flashdrive), so I knew, install or no install, it will run on it. I'm going to eventually upgrade to win 11, since the win 11 setup had the nerve to tell me that my old laptop (old, but still a lot newer than this old thing) was "insufficient" to install win 11 on. What nerve! Just for that, I'm going to make it work on this old junker, just to make a statement, and because I think it's really funny, for some reason.

PS: Having a full installation running on a flashdrive in my pocket is unbelievably useful, and comes in handy more often, and in more ways than I ever expected. IT people should always have one on their person, for any number of reasons, "Hey, Rocky! Watch me pull an operating system out of my ass!"
 

MicroSuck

Member
Now that I have that all done, and an itty-bitty little hard drive left over than I don't need, it has become my new lab monkey, something I can use and abuse for my own education and entertainment. And I am messing around with third party (third person?) image deployment tools, namely Flashboot, Rufus, and one called "Coolinstall" that was written and posted by another member of one of my forums, each of which does something interesting that the others can't.
And here is what only Rufus does that is interesting, it has a neat formatting option, it's BIOS/MBR format also supposedly works for booting EFI. And the way they did it is very cool. The "EFISECTOR" (fat12) partition is at the END of the physical disc, not the beginning, like they usually are. And the boot sector (physical disc sector "0", partition table and MBR) has a "press any key to boot from USB" feature like the "boot.bin" on the windows installation DVD. Also, sector 6 is supposed to be reserved for a backup copy of sector 0, but in this case, there is a conventional, no "press any key" boot sector there. I presume that is so anyone who knows WTF they are doing (who have Winhex, and not afraid to use it!) can use either one. Too bad I can't get a fresh install on this machine (they always fail half way through, for one reason or another, win 11 reported that it can't be configured to run on it, win 10 just reboots over and over, right after "select language and timezone"), so I can only use systems that were originally installed on another machine (my flashdrive, and the HDD out of my now dead laptop).
The 3 programs I am using deploy windows from windows, they aren't supposed to be bootable, like the windows setup DVD. However, I built a cool windows PE build, PE being the bootable system on said windows DVD, just for GP, so I adapted that to run those, and substituted it for the standard one on the DVD with a menu GUI, and threw in the windows 11 (the original that came with win 11, YUCK!!!), and the one from an older version of Win 10 (not sobbishly picky about what it will install on), just because I could. I can also run a bunch of other useful tools, even more than "Hirren's" boot disc, I know, because I took all of them, and added a few of my favorites, for my own use (like winhex, diskgenius, and the "Aomei" boot disc, which Hirren's started out with), and that is what I now consider to be the perfect windows installation disc. I had lots of fun with that. Anyway, that's how I've been able to get away with installing 10 and 11 onto MBR discs. I just wish I could get EasyBCD to run under windows PE, that's the last big bump in my road.
 
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