Port 80 occupied by another program

Problem: trying to start an Apache server on port 80 fails due to the fact that the 80 is not available.

When accessing the port, the following message appears: “HTTP Error 404. The requested resource is not found.”

Steps to correct the problem:

  1. netstat -ano | findstr :80
  2. Windows Task Manager with PID column enabled;
  3. Under the identified PID a program named system is shown (ntoskrnl.exe when accessing the properties option)
  4. After more research, it appears that Windows Kerner runs an IIS instance automatically for certain applications. Uninstall the applications to open port 80. In my case, it was Microsoft SQL Server, which I uninstalled from Control Panel.