If you are using Oracle Linux cloud images available from https://yum.oracle.com/oracle-linux-templates.html and at some point it does not boot up again and you see it is stuck in the bootloader (grub> prompt), then here are some steps to help you boot it up again. I have used them to rescue OL8 systems.

Oracle Support has a note “Oracle Linux: How to Recover a Non-Booting GRUB2 After Kernel Update (Doc ID 2898390.1)” but these steps do not perfectly work for the provided cloud image.

First check what disk devices are available, for the cloud image you should see this

grub> ls
(hd0) (hd0,msdos1) (hd0,msdos2)

Then check what Linux kernels you have available on this system. You should see vmlinuz ja initramfs file (files) with the matching version number.

grub> ls (hd0,msdos1)/
vmlinux-5.4.17-2136.342.5.el8uek.x86_64 initramfs-5.4.17-2136.342.5.el8uek.x86_64.img

Now boot it up

insmod lvm
insmod normal
insmod gzio
insmod part_gpt
insmod xfs
set root=(hd0,msdos1)
linux /vmlinux-5.4.17-2136.342.5.el8uek.x86_64 root=/dev/mapper/vg_main-lv_root
initrd /initramfs-5.4.17-2136.342.5.el8uek.x86_64.img
boot

After that the system should boot up as normal.

The Oracle Support note claims this can happen due to broken grub.cfg file, but at least the cases I’ve seen grub.cfg has been fine and regenerating it, as the support note recommends, had no help. But at least can temporarily boot up the system again.