BIOS continually resetting to UEFI [Solved]

[RedGreen925]

That sounds like it could work very well indeed! Thank you for the suggestion! To be honest, it sounds a bit over my head but I'm sure if I research those steps carefully I should be able to get it done. Thanks for the problem-solving attitude, I appreciate the suggestion.

It is actually fairly simple to do once you know how to do it. Firstly you need the external drive install confirmed working on the machine you will install onto. When you have that done you use the gdisk program in terminal window to partition the drive inside the machine with the tiny ESP/EFI partition at the start for the /boot/efi that is used by such a machine, this is set as type ef00 (EFI System Partition) when creating and formatted vfat. A second normal partition for the install on the machine set type 8300 linux and formatted with your file system of choice, I use ext4 for ages now it works well.

Then you can use the rsync to copy the running external drive system to the partition you have made for root on the internal drive and copy the external drive ESP/EFI partition to the internal one as well. Then you need to edit three files on an EFI system for it to boot, the grub.cfg that is in the /EFI/debian/ in the ESP/EFI partition to change the UUID in it to use the internal drive UUID. There is second grub.cfg file in the internal drive /boot/grub/ that has to be changed to the new internal UUID to be used. Lastly the internal drive /etc/fstab needs to have both the new / UUID of the previous two changes put into it and the new /boot/efi internal UUID so it will know where to mount the file systems once the external is removed and not used anymore.

I have done this so many times I have lost count it works every time without fail as long as I remember to change the UUIDs when doing it manually and every time when using my script I have written to do it to any of the fourteen different combinations of drives and machines I use that for. When you have working external drive booting in EFI mode on your machine let me know and I will provide step by step commands to get it done for you.

[xtac]

@j2mcgreg I used Rufus first but couldn't boot from UEFI, then Ventoy and had the same issues. No extra changes to settings when creating the Bootable USBs if that's what you meant. Do you recommend another tool?

[xtac]

@RedGreen925 . Wow, that sounds kinda interesting and daunting, but you've got me curious and you seem to explain things clearly. It also sounds like less work than wiping my SDD and starting everything again, but that's the only method I know I'm wondering for your first step if I can do a fresh install to USB or memory card and clone from there as my only other laptops have Windows on them? Perhaps we can start a new thread for this discussion or maybe if you one day feel like writing a tip/guide post about it in case anyone else ever has the same problem as me? I'll be breaking the forum rules to continue bumping this current topic when our discussion is unrelated to my title.

[RedGreen925]

I'm wondering for your first step if I can do a fresh install to USB or memory card and clone from there as my only other laptops have Windows on them?

Yes anything will work as long as you can boot on it and install in EFI mode to the drive you want to use. They you take the new install boot on problem machine in EFI mode use it to confirm it works. Once working then this is the time you wipe the problem machine internal drive to clone onto.

[j2mcgreg]

@xtac wrote:

I used Rufus first but couldn't boot from UEFI, then Ventoy and had the same issues. No extra changes to settings when creating the Bootable USBs if that's what you meant. Do you recommend another tool?

I just tested this with my Aspire V5, In order to get the Aspire V5 to boot with UEFI active, I had to configure Rufus to use GPT partitioning, If I instead just accepted the default Rufus settings, the Aspire balked.

[xtac]

@j2mcgreg Wooow! Thank you soooo much! I just always used default settings as 90% of the time I have no idea what I'm doing. I'm definitely going to try your solution.

[FullScale4Me]

@xtac wrote:

I used Rufus first but couldn't boot from UEFI, then Ventoy and had the same issues. No extra changes to settings when creating the Bootable USBs if that's what you meant. Do you recommend another tool?

I just tested this with my Aspire V5, In order to get the Aspire V5 to boot with UEFI active, I had to configure Rufus to use GPT partitioning, If I instead just accepted the default Rufus settings, the Aspire balked.

Rufus, as many users assume, picks a likely option. Not always does it pick the correct one for the intended use. See Rufus section of MX Linux Quick-Start Guide PDF, 399 Kb, illustrated, last updated: August 10, 2025. I am the author.

Newer PCs should have no Legacy/CSM support as an option. This was raised as a security issue some time ago by the UEFI standards group (Intel, Microsoft and all th big PC makers). IIRC it was pre-2020 timewise. For some reason, I can't find an exact date or standard .x revision level.