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Troubleshot Port 80 Being Blocked on a Local Dev Server

I came across a strange issue when trying to do some development on a Notes 9 server that’s running locally on my development machine. When the server started, it threw an error message in the console, saying “HTTP Server: Error – Unable to Bind port 80. port may be in use or user needs net_privaddr privilege.”


What really threw me off is that I’ve used this server several times already and haven’t had this problem.

Fortunately, it’s generally easy to figure out what’s blocking the port.

If you open up a command prompt and type netstat -an -o, you’ll get a list of all ports in use. In my case, the process ID was 4904.


Note the PID column — it lists the process ID of the task.

Scroll to find what’s listening on port 80 (TCP and get the process ID.

Next, open up the Task Manager. If you don’t see the PID column in the list of Processes, click on the View menu and choose Select Columns… and add the PID column.

Port80Block_TaskMgr_ProcessIDNow you can locate the process that is blocking port 80 and shut it down. As you can see in the screen shot above, the task with process ID 4904  was Skype!

Once that was shut down, the server was able to start and use port 80.