Django项目部署到Heroku后出现ModuleNotFoundError: No module named 'my_app.urls'错误的解决咨询

Let's walk through the most common fixes for this issue, since your local setup works fine but Heroku is throwing this error:

1. Make sure your my_app directory is tracked by Git #

Heroku only deploys files that are committed to your Git repository—it’s easy to accidentally forget to add new app directories.

• Run git status in your local project root. Look for my_app/ in the "Untracked files" section.
• If it’s missing, add and commit it:

  git add my_app/
  git commit -m "Add my_app directory and all its files"
  git push heroku main
  

• Double-check that my_app/urls.py is included in the commit with git show HEAD -- my_app/urls.py.

2. Verify your Python path on Heroku #

Sometimes Heroku’s environment doesn’t include your project root in the Python path, which makes it unable to locate my_app.

• Add these temporary debug lines to your settings.py:

  import os
  import sys
  
  print("BASE_DIR:", BASE_DIR)
  print("Python sys.path:", sys.path)
  

• Deploy this change, then check your Heroku logs with:

  heroku logs --tail
  

• If BASE_DIR (your project root) isn’t in sys.path, add it manually in settings.py:

  if BASE_DIR not in sys.path:
      sys.path.append(BASE_DIR)
  

• Remove the print statements once you confirm it works.

3. Clear Heroku's build cache #

Old build caches can sometimes cause module resolution issues, even if your code is correct.

• Purge the cache and redeploy:

  heroku repo:purge_cache -a your-app-name
  git push heroku main
  

  Replace your-app-name with the name of your Heroku app.

4. Fix ALLOWED_HOSTS for DEBUG=False issues #

While this isn’t directly causing the ModuleNotFoundError, when DEBUG=False, Django requires properly configured ALLOWED_HOSTS to avoid 500 errors.

• Update your settings.py to include your Heroku app’s domain:

  ALLOWED_HOSTS = ['your-app-name.herokuapp.com', 'localhost', '127.0.0.1']
  

• For a flexible setup, use an environment variable:

  import os
  ALLOWED_HOSTS = os.environ.get("ALLOWED_HOSTS", "localhost,127.0.0.1").split(",")
  

  Then set the ALLOWED_HOSTS variable in Heroku’s dashboard (Settings > Config Vars) to your app’s domain.

5. Double-check your INSTALLED_APPS configuration #

While you’ve already added my_app to INSTALLED_APPS, try using the full config path just in case:

INSTALLED_APPS = [
    # ... default apps
    'my_app.apps.MyAppConfig',  # Match the config class in my_app/apps.py
]

You can confirm the exact name in my_app/apps.py (the name attribute in the MyAppConfig class should be my_app).

After each step, deploy your changes and check if the error is resolved. Always use heroku logs --tail to get detailed server error messages—this will help you narrow down any remaining issues.

内容的提问来源于stack exchange，提问作者Abdulla Shafi