Syslinux "Missing OS" after expanding to the left the partition with /boot

Question

I have a GPT partitioned drive. Its a bit of a mess so I was starting to sort everything out.

/dev/sda2 is an ArchLinux install and the location of /boot with syslinux being used.

/dev/sda1 is a ubuntu install.

I plan soon to complete do away with the ubuntu partition but for now just make it smaller and the increased /dev/sda2 in size by moving the start of it up to the end of the ubuntu partition.

However now syslinux will not start and the computer just comes up with a missing os error.

Acording to gparted /dev/sda2 does still have the boot flag.

I have used a live CD to check with gparted If the partitions are still ok and everything does seem fine it just cant boot.

What should I do to get syslinux booting again?

Answer 1

I assume this is you. So, if so, since you are on Arch Linux have you tried to reinstall the Syslinux bootloader?

(As root): syslinux-install_update -i -a -m

syslinux-install_update script to automatically install the bootloader (-i), mark the partition active by setting the boot flag (-a), and install the MBR boot code (-m)

Since you have a GPT partitioning scheme ensure gptfdisk is installed if not already or the above root command will fail.

Ensure that /boot/syslinux/syslinux.cfg actually points to the right partitions (e.g. /dev/sda2) for your specific set-up.