Fix error on website server

Hello,

We have a WordPress install on Bitnami, on CentOS. The site went down, with error:

503 Service Unavailable
No server is available to handle this request.

Logs show:

AH01630: client denied by server configuration

Did some googling, possibly to do with apache 2.4 vs 2.2 and permissions?! I got lost looking for the rite files. Can anyone assist asap?

Can give the SSH login

Thank you!