Troubleshooting for Error: Apache Shutdown unexpectedly

Question

I installed XAMPP recently , in the panel when starting apache service the following error message was displayed

09:04:36  [Apache]  Error: Apache shutdown unexpectedly.
09:04:36  [Apache]  This may be due to a blocked port, missing dependencies, 
09:04:36  [Apache]  improper privileges, a crash, or a shutdown by another method.
09:04:36  [Apache]  Press the Logs button to view error logs and check
09:04:36  [Apache]  the Windows Event Viewer for more clues
09:04:36  [Apache]  If you need more help, copy and post this
09:04:36  [Apache]  entire log window on the forums
09:08:10  [Apache]  Problem detected!
09:08:10  [Apache]  Port 80 in use by "Unable to open process" with PID 4!
09:08:10  [Apache]  Apache WILL NOT start without the configured ports free!
09:08:10  [Apache]  You need to uninstall/disable/reconfigure the blocking application
09:08:10  [Apache]  or reconfigure Apache and the Control Panel to listen on a different port

To solve this problem I consulted this video where the author adds the code snippet below to his file httpd.conf :

#Listen [::]:80

This solved the problem but I would like to know what it means exactly ?

Answer 1

When httpd is started, it connects to some port and address on the local machine and waits to receive requests. This causes the server to accept connections on port 80 for an interface and port. [::] means it’s for any IP, that in your case, any IP on port 80. By default, it listens to all addresses on the machine. However, it may need to be configured to listen on some specific ports, or only on selected addresses, or a combination of both.

Details

• Binding to Addresses and Ports