URGENT Internal Server Error

ubuntu 18.04
ghost Version 3.12.1

I’ve been online for a couple of years now, I’ve never had this problem, I’ve never changed the server.

suddenly the site encounters an internal server error, I can’t connect from frontend or backend, once in 10 I can connect, immediately after I find the error again.

below are a couple of screens:

what could be the problem?
it is very urgent, i have many active users but i can easily lose them.

which log files can help solve the problem?

I also tried to restart the server, the problem persists.




ghost doctor and ghost status show no errors