title: Heroku worker suddenly crashes, logs don't show any of my scripts. What happened?
body: <p>I have a flask, gunicorn, postgresql project hosted on heroku and it suddenly failed. I can access the logs, but there is no script that I wrote, so I am confused. I haven't added anything between "working" and "not working" so I don't know where I can start.</p>
  
  <p>The log can be found in this <a href="https://pastebin.com/fFiLmMxC" rel="nofollow noreferrer">pastebin</a>.
  The last part is:</p>
  
  <pre><code>2020-02-06T21:09:02.748093+00:00 app[web.1]: from werkzeug.contrib.cache import FileSystemCache
  2020-02-06T21:09:02.748100+00:00 app[web.1]: ModuleNotFoundError: No module named 'werkzeug.contrib'
  2020-02-06T21:09:02.748789+00:00 app[web.1]: [2020-02-06 21:09:02 +0000] [10] [INFO] Worker exiting (pid: 10)
  </code></pre>
  
  <p>I tried to add werkzeug to the requirements.txt, but that did not help. Which would have been strange anyway, because it was working fine without the change in the requirement.</p>
  
  <p>If you could help me reducing the requirements.txt, it would be greatly appreciated. </p>
  
  <p>Original requirements.txt:</p>
  
  <pre><code>cs50
  Flask
  Flask-Session
  requests
  gunicorn
  psycopg2-binary
  openpyxl
  </code></pre>
  
  <p>New, working ones:</p>
  
  <pre><code>astroid==2.3.3
  attrs==19.3.0
  Authlib==0.13
  autopep8==1.5
  awscli==1.17.9
  backports.shutil-get-terminal-size==1.0.0
  backports.shutil-which==3.5.2
  beautifulsoup4==4.8.2
  botocore==1.14.9
  bs4==0.0.1
  cairocffi==1.1.0
  CairoSVG==2.4.2
  certifi==2019.11.28
  cffi==1.13.2
  chardet==3.0.4
  check50==3.0.10
  Click==7.0
  colorama==0.4.1
  compare50==1.1.2
  cryptography==2.8
  cs50==5.0.3
  cssselect2==0.2.2
  cycler==0.10.0
  defusedxml==0.6.0
  docutils==0.15.2
  EditorConfig==0.12.2
  et-xmlfile==1.0.1
  Flask==1.1.1
  Flask-Session==0.3.1
  help50==3.0.0
  html5lib==1.0.1
  icdiff==1.9.1
  idna==2.8
  ikp3db==1.4.1
  intervaltree==2.1.0
  isort==4.3.21
  itsdangerous==1.1.0
  jdcal==1.4.1
  jellyfish==0.7.2
  Jinja2==2.11.1
  jmespath==0.9.4
  jsbeautifier==1.10.3
  kiwisolver==1.1.0
  lazy-object-proxy==1.4.3
  lib50==2.0.7
  logger==1.4
  MarkupSafe==1.1.1
  matplotlib==3.1.3
  mccabe==0.6.1
  natsort==7.0.1
  nltk==3.4.5
  numpy==1.18.1
  oauthlib==3.1.0
  openpyxl==3.0.3
  pandas==1.0.0
  pexpect==4.8.0
  Pillow==7.0.0
  plotly==4.5.0
  psycopg2-binary==2.8.4
  ptyprocess==0.6.0
  pyasn1==0.4.8
  pycodestyle==2.5.0
  pycparser==2.19
  Pygments==2.5.2
  pylint==2.4.4
  pylint-django==2.0.13
  pylint-flask==0.6
  pylint-plugin-utils==0.6
  pyparsing==2.4.6
  PyPDF2==1.26.0
  Pyphen==0.9.5
  python-dateutil==2.8.1
  python-magic==0.4.15
  pytz==2019.3
  PyYAML==5.2
  render50==3.1.3
  requests==2.22.0
  requests-oauthlib==1.3.0
  retrying==1.3.3
  rsa==3.4.2
  s3cmd==2.0.2
  s3transfer==0.3.2
  six==1.14.0
  sortedcontainers==2.1.0
  soupsieve==1.9.5
  SQLAlchemy==1.3.13
  sqlparse==0.3.0
  style50==2.7.4
  submit50==3.0.2
  termcolor==1.1.0
  tinycss2==1.0.2
  tqdm==4.42.1
  twython==3.7.0
  typed-ast==1.4.1
  urllib3==1.25.8
  virtualenv==16.7.9
  WeasyPrint==49
  webencodings==0.5.1
  Werkzeug==0.16.1
  wrapt==1.11.2
  gunicorn
  </code></pre>