title: Supervisor: ERROR (spawn error) when trying to launch gunicorn
body: <p>I have been trying to setup gunicorn with supervisor <a href="https://realpython.com/blog/python/kickstarting-flask-on-ubuntu-setup-and-deployment/" rel="noreferrer">per these instructions</a>. However when I run</p>
  
  <pre><code>sudo supervisorctl reread
  sudo supervisorctl update
  sudo supervisorctl start Server-CardLearning
  </code></pre>
  
  <p>I get the error <code>Server-CardLearning: ERROR (spawn error)</code>.</p>
  
  <p>My configuration file is simple. </p>
  
  <pre><code>[program:Server-CardLearning]
  command = gunicorn app:app -b localhost:8000
  directory = /home/alexg/www/&lt;flask project&gt;
  user = www-data
  </code></pre>
  
  <p>I get the following errors in my log file.</p>
  
  <pre><code>...
  ...
  2017-11-30 13:48:52,276 INFO gave up: Server-CardLearning entered FATAL state, too many start retries too quickly
  2017-11-30 13:49:10,595 INFO spawnerr: unknown error making dispatchers for 'Server-CardLearning': ENOENT
  2017-11-30 13:49:11,597 INFO spawnerr: unknown error making dispatchers for 'Server-CardLearning': ENOENT
  2017-11-30 13:49:13,599 INFO spawnerr: unknown error making dispatchers for 'Server-CardLearning': ENOENT
  2017-11-30 13:49:16,603 INFO spawnerr: unknown error making dispatchers for 'Server-CardLearning': ENOENT
  2017-11-30 13:49:16,603 INFO gave up: Server-CardLearning entered FATAL state, too many start retries too quickly
  2017-11-30 13:58:12,101 INFO spawned: 'Server-CardLearning' with pid 13725
  2017-11-30 13:58:12,560 INFO exited: Server-CardLearning (exit status 3; not expected)
  2017-11-30 13:58:13,563 INFO spawned: 'Server-CardLearning' with pid 13730
  2017-11-30 13:58:13,982 INFO exited: Server-CardLearning (exit status 3; not expected)
  2017-11-30 13:58:15,986 INFO spawned: 'Server-CardLearning' with pid 13735
  2017-11-30 13:58:16,411 INFO exited: Server-CardLearning (exit status 3; not expected)
  2017-11-30 13:58:19,416 INFO spawned: 'Server-CardLearning' with pid 13742
  2017-11-30 13:58:19,842 INFO exited: Server-CardLearning (exit status 3; not expected)
  2017-11-30 13:58:20,843 INFO gave up: Server-CardLearning entered FATAL state, too many start retries too quickly
  ...
  ...
  2017-11-30 14:10:29,728 INFO spawned: 'Server-CardLearning' with pid 13901
  2017-11-30 14:10:29,957 INFO exited: Server-CardLearning (exit status 2; not expected)
  2017-11-30 14:10:30,961 INFO spawned: 'Server-CardLearning' with pid 13902
  2017-11-30 14:10:31,193 INFO exited: Server-CardLearning (exit status 2; not expected)
  2017-11-30 14:10:33,200 INFO spawned: 'Server-CardLearning' with pid 13903
  2017-11-30 14:10:33,436 INFO exited: Server-CardLearning (exit status 2; not expected)
  2017-11-30 14:10:36,443 INFO spawned: 'Server-CardLearning' with pid 13904
  2017-11-30 14:10:36,681 INFO exited: Server-CardLearning (exit status 2; not expected)
  2017-11-30 14:10:37,682 INFO gave up: Server-CardLearning entered FATAL state, too many start retries too quickly
  </code></pre>
  
  <p>Where am I going wrong? I have tried some things I saw on stack overflow, but nothing proved to be relevant to this problem.</p>