root@366956-cr21510:~# systemctl restart mongodb
root@366956-cr21510:~# mongo
MongoDB shell version v3.6.3
connecting to: mongodb://127.0.0.1:27017
2021-03-22T16:34:37.670+0200 W NETWORK  [thread1] Failed to connect to 127.0.0.1:27017, in(checking socket for error after poll), reason: Connection refused
2021-03-22T16:34:37.670+0200 E QUERY    [thread1] Error: couldn't connect to server 127.0.0.1:27017, connection attempt failed :
connect@src/mongo/shell/mongo.js:251:13
@(connect):1:6
exception: connect failed
root@366956-cr21510:~# sudo service mongodb status
● mongodb.service - An object/document-oriented database
   Loaded: loaded (/lib/systemd/system/mongodb.service; enabled; vendor preset: enabled)
   Active: failed (Result: exit-code) since Mon 2021-03-22 16:34:34 EET; 7s ago
     Docs: man:mongod(1)
  Process: 28073 ExecStart=/usr/bin/mongod --unixSocketPrefix=${SOCKETPATH} --config ${CONF} $DAEMON_OPTS (code=exited, status=1/FAILURE)
 Main PID: 28073 (code=exited, status=1/FAILURE)

Mar 22 16:34:34 366956-cr21510.tmweb.ru systemd[1]: Started An object/document-oriented database.
Mar 22 16:34:34 366956-cr21510.tmweb.ru mongod[28073]: 2021-03-22T16:34:34.584+0200 F CONTROL  [main] Failed global initialization: FileNotOpen: Failed to open "/var/log/mongodb/mongodb.log"
Mar 22 16:34:34 366956-cr21510.tmweb.ru systemd[1]: mongodb.service: Main process exited, code=exited, status=1/FAILURE
Mar 22 16:34:34 366956-cr21510.tmweb.ru systemd[1]: mongodb.service: Failed with result 'exit-code'.