My web server (VM) was running perfectly with no issues and we made no changes in the configurations. Suddenly, we started finding issues accessing (eg. request to website goes timed out) the server, and found it killed Apache/mysql process and in the console we are getting the errors as per the attached image.
We restarted the server and the issue got fixed for a while but appeared again.
I have no idea what caused this issue. How we may fix it or where to look for some more clues?
Update: from Apache error log I see:
[error] server reached MaxClients setting, consider raising the MaxClients setting