Debain has Grub and when I select Mint to load I get the message "Error: Out of memory hit any key to continue" hitting any key does nothing only Ctrl Alt Delete to reboot. I tried a few more times then switched to Ubuntu and took control of Grub. Rebooted and selected Mint and it loaded fine.
Edit: Also on that subject Debian Grub doesn't recognise Windows 11. This is on laptop; where on PC with W10 it loads fine. This may have something to do with UEFI; not sure though.
It is the PC Debian with Grub error message.

You have not made it clear what problem you are trying to solve.

Debian, in accordance with Grub upstream, switched to not by default including Windows in its Grub menu. You can easily change that by editing /etc/default/grub to include GRUB_DISABLE_OS_PROBER="false" (instead of true), and then regenerating grub.cfg. Due to this upstream switch, more distros are probably making the same change. On UEFI systems this is a minor issue, because boot selection of OS can be made via the UEFI BIOS BBS menu.

The out of memory is error is commonly encountered when there are multiple versions of Grub on the installed system. Only one Grub is actually needed per PC or laptop if GRUB_DISABLE_OS_PROBER="true" is employed on the installed Grub, and/or if optional features of Grub are appropriately configured.

default/grub OS_Prober was set to false.

On the error message: All was fine last time I booted Mint and I don't think I did anything to cause it. I did update-grub in Debian but that didn't help. I have Grub on Ubunru and it's fine there. Thanks for the help

Caveat: I use neither Debian nor Ubuntu.

I note this error report from early '23, but later reports included as well. I wonder if Debian has regressed (or never implemented) the fix ...

what happens when you use bios boot menu if you have one. key to access it varies per system. f10 or f12 though could be something else.

how much free space you got in your uefi boot partition? seen the problem before with old boot mbr on platter drives with large kernel either corrupt or too big for mbr.

after changing the os prober setting you need to run sudo update-grub

Yes I can select Ubuntu or Windows in Boot menu; not necessary though. All I did was select Ubuntu in Demian's Grub and give Grub to Ubuntu where all four OS's boot fine. So it really isn't a problem, but I like to try and figure out these glitches.
My EFI on sda1 has 1GB and 40.56 MiB used. Yes aware of updating Grub.

Does your EFI partition have directories named Microsoft, ubuntu and debian? Are all of these OS's on the same physical hard drive?

Have deleted former input as was on wrong computer. So on laptop Debian grub worked fine; on PC now and using Ubuntu for Grub. So yes all on the same drive. 1GB EFI on sda1 flagged "esp boot". Upped from a on to 2 TB ssd.
Only 58 MiB's used on EFI out of 1GB.

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