A 404 Not Found error in Nginx means that the server was unable to locate the page or resource that a user was trying to access. This can happen for a variety of reasons, and the steps to fix it vary based on the cause. Here’s a guide on how to troubleshoot and resolve a 404 Not Found error in Nginx.

1. Check for Typing Errors in the URL

The first and simplest step is to ensure that the URL has been entered correctly. Typing errors are common and can lead to a 404 error. Double-check that the path and file name are correct in the address bar of your browser.

2. Verify That the Requested Resource Exists

Make sure that the file or webpage you are trying to access actually exists on the server. Check for correct filenames, locations, and extensions.

3. Review Nginx Configuration Files

The Nginx configuration file, typically found at `/etc/nginx/nginx.conf` or `/etc/nginx/sites-available/default`, dictates server block rules which determine how requests are handled. Look for typos or incorrect directives that might be causing issues with locating the correct resources.

4. Examine .htaccess Rules

If you’ve migrated from an Apache server, you may have rewrite rules in an `.htaccess` file which could create conflicts in Nginx, as it does not natively support .htaccess files. Instead, these rules need to be included in your site’s Nginx configuration file.

5. Check File and Directory Permissions

File permissions can also cause a 404 error if the server does not have permission to access the requested files or directories. Use `ls -l` to examine permissions and `chmod` commands to set them properly.

6. Monitor Error Logs

Nginx logs can provide detailed insights into what caused a particular error. The access log and the error log often located at `/var/log/nginx/access.log` and `/var/log/nginx/error.log`, respectively, are valuable resources for diagnosing issues.

7. Reload Or Restart Nginx Server

After making configuration changes or updates, it’s necessary to reload or restart Nginx for changes to take effect. Use `nginx -s reload` to safely reload configurations without dropping connections or `systemctl restart nginx` (or equivalent command) based on your Linux distribution.

8. Check DNS Settings and Propagation

DNS issues can also result in a 404 error if your domain name doesn’t resolve correctly to your server’s IP address. Ensure that your domain’s DNS settings are correct and fully propagated.

 Conclusion

In most cases, fixing a 404 Not Found Nginx error involves checking for typos, ensuring resource availability, investigating configuration settings, adjusting permissions, tracking logs for errors, and potentially verifying DNS settings. By methodically passing through each of these steps, you’ll cover most bases for common issues resulting in this type of error.