404 error on Apache

1. A 404 error might be caused by a virtualhost configuration issue. (For example: if the document root is set to a directory that doesn't exist.) You can check your Apache configuration file for errors using the below:

   Debian and Ubuntu:

   apache2ctl -t
   

   Fedora and CentOS:

   httpd -t
   

2. If you see the below failure in your logs, check on the status of Apache:

   [FAILED] Failed to start The Apache HTTP Server.
   

   Check Apache status:

   systemctl status apache2.service
   

   View the associated logs:

   journalctl -xe
   

3. As for other general troubleshooting steps, if you recently made changes to your server that don't seem to be taking effect, it might help to restart or reload Apache:

   Debian and Ubuntu:

   /etc/init.d/apache2 reload
   

   Fedora and CentOS:

   /etc/init.d/httpd reload
   

4. Check your Apache logs to see if they point to anything specific. You can use tail -f to live-reload your error logs:

   tail -f /var/log/apache2/error.log
   

For more general troubleshooting steps, please see:

https://www.linode.com/docs/troubleshooting/troubleshooting-common-apache-issues/