Sorry for the late answer.

1.) MongoDB is installed directly.
2.) Installed is version 3.6.5.
3.) The log of mongod only says that it started up. Everything before this is missing. Don't ask me why.
4.) Didn't see anything special inside syslog.

What we did now is that we watch over the system memory via SNMP.

$ free -h
              total        used        free      shared  buff/cache   available
Mem:           2.0G        236M        1.7G        1.2G         68M        1.8G
Swap:          4.0G        183M        3.8G

This doesn't look like a memory issue could happen. Noone is using the server atm. I go on there alone. Don't see anything special inside syslog. I will activate some SNMP sensors and hopefully see what happens shortly before it crashes.

Thanks for your try to help Baris!

What I did:

• Registered here with Github (social registration).
• I get automatically logged in.
• I directly went to my profile.
• Changed Username and Email (taken from Github).
• Now I saw the popup telling me that I still didn't confirm my email address.
• Checked my newly entered mailadress... nothing.
• Checked the mailaddress which came from Github. Yes a confirmation mail.
• Clicked on the link. "Invalid confirmation link".

I needed to resend the confirmation email manually before I could post.

What behaviour I would like to see:

• When I change my email address I need to get a new confrmation mail automatically (Opt-In active).

We are running nodeBB on a testserver at the moment. Sometimes (maybe once a week or less) the mongod seems to crash. The service is nonresponding and so nodeBB also goes down. I don't see anything that helps us inside the logs. nodeBB only tells me that it cannot connect to the database and mongod just shows when I restarted the service.

I would like to investigate this before we go productive. Is there any way to exactly see what causes this crashes? The server itself is a clean Ubuntu 16.04 LTS virtual server with nothing else running on it.

Regards,
Tekin