After setting large_dir flag with tune2fs for my ext4 filesystem on mdadm RAID1, Linux (Ubuntu 18) is no longer able to boot, showing "error: unknown filesystem". The lack of support is confirmed on https://wiki.archlinux.org/title/GRUB#error:_unknown_filesystem
Unfortunately tune2fs can't remove this flag, only set it.
I tried booting with rEFInd instead of Grub, but it doesn't show an option to start Ubuntu directly, only using Grub. Perhaps because the system partition is a raid array? Or maybe it doesn't support that flag either.
Another idea I have is converting the ext4 partition to another filesystem, perhaps btrfs. But I'm worried about destroying data.
Is there another way to repair the system?
