While trying to start apache from XAMMP I got the following error

"Port 80 in use by "Unable to open process" with PID 4!
Apache WILL NOT start without the configured ports free!
You need to uninstall/disable/reconfigure the blocking application
or reconfigure Apache and the Control Panel to listen on a different port"

This error usually appears when the port required for apache is utilized by some other process. I fixed the issue by stopping the process using Port 80. Read on to know the exact steps

port80-1

  1. Open XAMPP window and click on the Services button
  2. Go to World Wide Web Publishing Service and right click
    xampp-port-80
  3. Stop the process
  4. Now try restarting apache

The above steps fixed my issue, hope it helps.