Internal server error: docker restarting frequently but failing

Hello All,

nextcloud noob here. I just got handed over a nextcloud account with an internal server error and I need to solve this issue to get some data that was saved on it.
After struggling through many stack overflow and github pages I realised that while looking at the dockers, three of them just keep trying to restart themselves but it fails. Looking at the disc space used, I see that there are some disks that are full and I am not sure if that is the reason for the server error.

Could someone please point out as to what is wrong with the server and what could I do to check or rectify that?

I have heard that this has been happening frequently in the last few months. Most of the times nobody knows how it rectifies itself.

Thanks in advance,