Daily Fatal Error Unable to create lock file: Bad file descriptor (9) and Internal Server Error 500

Good Morning Everyone. I have a dedicated server with 2 NVMe Drives mounted as SoftRAID - RAID1. Since about 1 week ago I am getting an interesting error exactly at 10PM PST. Between 9-10PM what I see if cPanel is performing a backup for all of our accounts. We do have a very limited space on the server. 476 GB Storage out of which 300GB is used. So investigating this is what I found. (was not able to paste here on cPanel) Both of my drive's SMART shows disks are healthy, I had my server guys intervene and also they informed me things on the Hardware side are fine. What else I can do to investigate this further? Thank you.