If you work on Windows 10 machine and doing some HTTP stuff you may noticed that the port 80 is blocked even if you don't run any application that normally use it, like IIS, Apache, nginx or one of your own creations.
So, if you run something like
netstat -ano you may notice that port 80 is used by a process with PID 4, this is a system process, so stuff like
tasklist /fi "pid eq 4" won't help you a lot.
Further googling arround may show you that this can be the
Web Deployment Agent Service (MsDepSvc) but there is no such service on your machine, so what?
Guess what, if you have a SQL server installed on your machine then just turn of
SQL Server Reporting Services (SQLEXPRESS). Yes! no kidding, its so obvious that the reporting service uses port 80 just like the deployment service.