title: mongod.service: Failed at step USER spawning /usr/bin/mkdir: No such process
body: <p>I'm running ec2 instance of os Ubuntu 16.04.</p>
  
  <p>I recently tried to upgrade my mongodb from 3.2 to 3.6.</p>
  
  <p>And I tried to run <code>sudo service mongod start</code> and mongod service failed to start.</p>
  
  <p>Below is the error message.</p>
  
  <pre><code>mongod.service - High-performance, schema-free document-oriented 
  
  database
     Loaded: loaded (/etc/systemd/system/mongod.service; enabled; vendor preset: enabled)
     Active: failed (Result: exit-code) since Mon 2018-03-05 05:48:12 UTC; 11s ago
       Docs: https://docs.mongodb.org/manual
    Process: 18587 ExecStartPre=/usr/bin/mkdir -p /var/run/mongodb (code=exited, status=217/USER)
   Main PID: 16567 (code=exited, status=100)
  
  Mar 05 05:48:12 ip-172-31-18-34 systemd[1]: Starting High-performance, schema-free document-oriented database...
  Mar 05 05:48:12 ip-172-31-18-34 systemd[18587]: mongod.service: Failed at step USER spawning /usr/bin/mkdir: No such proc
  Mar 05 05:48:12 ip-172-31-18-34 systemd[1]: mongod.service: Control process exited, code=exited status=217
  Mar 05 05:48:12 ip-172-31-18-34 systemd[1]: Failed to start High-performance, schema-free document-oriented database.
  Mar 05 05:48:12 ip-172-31-18-34 systemd[1]: mongod.service: Unit entered failed state.
  Mar 05 05:48:12 ip-172-31-18-34 systemd[1]: mongod.service: Failed with result 'exit-code'.
  </code></pre>
  
  <p>And I never edited a single line of default <code>mongod.service</code> file.</p>
  
  <p>How can I fix this issue?</p>