Debugging urllib Issues

Using the urllib module for making HTTP requests in Python can sometimes run into issues. Here are some tips for debugging problems:

Check the URL

Make sure the URL you are trying to request is valid. Some things to check:

import urllib.request

url = "https://www.example.com/api?key=123" 
print(url) # inspect full URL being requested

Handle Exceptions

Wrap your urllib code in try/except blocks to catch errors:

import urllib.error

try:
    response = urllib.request.urlopen(url)
except urllib.error.URLError as e:
    print(f"URL Error: {e.reason}")

Common exceptions to handle:

Use Logging

The urllib module provides a logger to help debug issues:

import logging
import urllib.request

logger = logging.getLogger("urllib3")  
logger.setLevel(logging.DEBUG)

urllib.request.urlopen(url)

This will print debug info like the request headers, response code, etc.

Summary

Careful checking of request formation, handling errors properly, and liberal use of print statements can help uncover most urllib issues.