Grub boot menu didn’t show after reboot today morning. Only had the OpenSuse entry. I tried to see if I can find an answer in YaST, but couldn’t. I remember, some solution was there, but couldn’t find it. So looked around in the net and found the answer.
sudo os-prober
sudo grub2-mkconfig -o /boot/grub2/grub.cfg
The grub menu appeared.
That is only a repair after you got hit by the problem. But the problem is NOT created by the reboot. There must have been things done that broke your Grub configuration before that reboot. You better try to identify the root cause of this else it may happen again.
This is what happened.
The grub boot menu appeared, but with only one entry, the Opensuse one, but all other entries for other distros were missing. OpendSuse booted and ran well. Rebooted twice, but the full grub boot menu didn’t turn up. As the system is UEFI, I can get to the other distros, but I wanted to find out how to get the full menu back. So did the grub update and the whole grub menu came back. Before rebooting, that is yesterday, everything was good. Today, after rebooting, even with one solitary grub entry showing, the system worked well. So, don’t really know, what had gone wrong. I hadn’t done anything to the system, except installing few apps through YaST.
How to find that out? Everything works, as far I can gather.
Thanks for the explanation. It is thus unclear how this happened. Not a nice idea 
The only thing then is to be alert for the next time (which of course may never happen).
Does this happen, because the /boot/grub2/grub.cfg file is locked?
](https://imgbb.com/)https://i.ibb.co/pdV0kkG/Screenshot-20191102-194237.png
