Quick Summary
Error 520 is a general "Web server is returning an unknown error" message, meaning the origin server returned something unexpected or uninterpretable. This error typically indicates a problem with the origin server, not the client or Generic itself.
Common Causes
- Origin Server Crash: The origin web server crashed or is not responding to requests. This could be due to high traffic, resource exhaustion, or a software bug.
- Application Error: The application running on the origin server (e.g., PHP, Python) has encountered an unhandled exception or error. This can lead to an invalid response.
- Invalid Headers: The origin server is sending HTTP headers that are malformed or violate HTTP specifications. Generic fails to interpret the malformed headers.
- Too Many Connections: The origin server has reached its maximum number of allowed connections, preventing it from processing new requests.
- Timeout: The origin server took too long to respond to the request, exceeding a pre-defined timeout limit. Generic then reports a 520 error.
Step-by-Step Fixes
Method 1: Check Origin Server Status
Step 1: Verify that your origin server is running and accessible by pinging the IP address or hostname. Ensure basic network connectivity.
Step 2: Check the origin server's resource usage (CPU, memory, disk I/O). Overload can lead to instability.
Step 3: Examine the server's error logs (e.g., Apache error log, Nginx error log, application logs) for clues about the cause of the error.
Method 2: Review Recent Code Changes
Step 1: If the error started occurring recently, investigate recent code deployments or configuration changes on the origin server.
Step 2: Revert any changes that might be causing the error and monitor the server's behavior.
Method 3: Examine Application Logs
Step 1: Examine the application logs for any errors or exceptions that might be causing the unexpect response.
Step 2: Increase logging verbosity to capture more detailed information about request processing.
Method 4: Increase Timeout Settings
Step 1: If the origin server is under heavy load, consider increasing the timeout settings. This will allow the origin server longer to formulate it's repsonse.
Step 2: Increasing timeout settings must be balanced against potential denial-of-service attacks, so be careful.
Method 5: Contact Hosting Provider
Step 1: If you are unable to identify the cause of the error, contact your server hosting provider for assistance.
Step 2: Provide them with as much information as possible, including the time the error occurred, your troubleshooting steps, and any relevant log entries.