Fix 'cannot import default_ciphers from urllib3.util.ssl_' Error

The cannot import default_ciphers from urllib3.util.ssl_ error typically occurs when there’s a version mismatch or an incompatibility between urllib3 and other libraries that depend on it, such as requests. Below is a comprehensive guide to diagnosing and fixing this issue, structured for both search engine optimization and human readability.

Understanding the Error

The error arises because urllib3 has undergone changes in its internal structure, particularly in how SSL-related utilities are handled. The default_ciphers module, which was once directly importable, may have been moved or renamed in newer versions of urllib3. This often affects downstream libraries like requests, which rely on urllib3 for HTTP functionality.

Diagnosing the Issue

1. Check Installed Versions
   Verify the installed versions of urllib3 and requests:

   pip show urllib3 requests
   

2. Review Dependency Conflicts
   Some libraries may require specific versions of urllib3. Use pipdeptree to visualize dependencies:

   pip install pipdeptree
   pipdeptree
   

3. Inspect Import Statements
   Look for direct imports of default_ciphers in your code or third-party libraries. For example:

   from urllib3.util.ssl_ import default_ciphers
   

Solutions

1. Upgrade urllib3 and requests

Ensure both libraries are up to date:

pip install --upgrade urllib3 requests

If you need to downgrade urllib3 for compatibility, specify the version:

pip install urllib3==1.26.15

2. Replace Deprecated Imports

In newer versions of urllib3, default_ciphers may be accessed differently. Replace:

from urllib3.util.ssl_ import default_ciphers

with:

from urllib3.util import SSL_DEFAULT_CIPHERS as default_ciphers

3. Pin Dependency Versions

In your requirements.txt or setup.py, explicitly pin compatible versions:

urllib3==1.26.15
requests==2.28.1

4. Patch Third-Party Libraries

If the issue stems from a third-party library, consider forking the repository and updating the import statement. Alternatively, contact the library maintainers to report the issue.

5. Use a Virtual Environment

Isolate dependencies to avoid conflicts:

python -m venv myenv
source myenv/bin/activate  # On Windows: myenv\Scripts\activate
pip install -r requirements.txt

Example Fix for requests Library

If requests is causing the error, ensure it’s using a compatible urllib3 version:

pip install requests==2.28.1 urllib3==1.26.15

Preventing Future Issues

• Regularly update dependencies using pip list --outdated.
  
• Monitor release notes for breaking changes in urllib3 and requests.
  
• Use tools like pip-tools to manage dependencies effectively.

FAQ Section

Conclusion

The cannot import default_ciphers from urllib3.util.ssl_ error is typically resolved by updating or downgrading urllib3 and ensuring compatibility with dependent libraries. By following the steps outlined above, you can effectively diagnose and fix the issue while maintaining a secure and stable application environment.