Common HTTP Errors

Common Server Errors and Solutions

1. 404 Not Found
   This error occurs when the server cannot find the requested page. It’s often due to a broken link or incorrect URL.

   Solution: Check the URL for any typos, verify the page exists, and ensure it is properly linked on the website.

2. 500 Internal Server Error
   This is a generic error indicating a problem with the server. It could be due to a misconfiguration, server overload, or a malfunctioning script.

   Solution: Review server logs for specific error details. Check your .htaccess file or web server configuration for errors. Restart the server and check for updates or bugs in the code.

3. 503 Service Unavailable
   This error indicates that the server is temporarily unable to handle the request. It could be due to server maintenance, overload, or issues with the server’s backend.

   Solution: Wait for the server to become available, check for server maintenance schedules, and ensure that the server has sufficient resources to handle requests.

4. 403 Forbidden
   The server is refusing to allow the requested action. This typically occurs due to permission settings or restrictions on certain files or resources.

   Solution: Check the file or directory permissions. Ensure that the web server has appropriate access rights to the files it needs to serve.

5. 502 Bad Gateway
   A 502 error occurs when a server acting as a gateway or proxy receives an invalid response from an upstream server.

   Solution: Check the configuration of the reverse proxy or gateway. Verify network connections and ensure upstream servers are online.

6. 504 Gateway Timeout
   A 504 error occurs when the server times out waiting for a response from an upstream server.

   Solution: Increase the timeout settings on the server. Check network connectivity to upstream servers and ensure they are responsive.

7. 401 Unauthorized
   This error occurs when a user attempts to access a resource without proper authentication.
   Solution: Ensure the correct login credentials are provided. Check if the resource requires special permissions or a different authentication method (e.g., OAuth, JWT).

8. 400 Bad Request
   This error indicates that the server cannot understand the request due to malformed syntax.

   Solution: Review the request syntax and headers. Check for malformed URLs, incorrect query strings, or other invalid input from the client.

Microsoft Support for Server Errors

For a detailed guide on troubleshooting server errors, visit the following Microsoft Support page:

• Microsoft KB 943891 - Troubleshooting HTTP Errors

This page offers a comprehensive guide on diagnosing and fixing server errors on IIS, covering common issues and their resolutions. It also provides steps to troubleshoot errors based on different versions of IIS and server configurations.