Find and terminate a Windows Process by Port

Two common ports that may experience this error include 3000 and 8081, but can be any port.

Find the Process ID (PID)

For this, we can use netstat -a -o -n to list all active connections.

C:\Users\user> netstat -a -o -n

Active Connections

Proto  Local Address          Foreign Address        State           PID
...
TCP    [::]:8080              [::]:0                 LISTENING       3664
...

In the list that gets spat out, find the line that has a Local Address ending in the port you want to terminate - in this case we see:8080. Note the value in the PID column - we'll need that in a minute. NOTE: This value will most likely be different each time you start your program.

Confirm that PID is for the program in question

This step is optional, but I like to double check that I'm targeting the correct process before I terminate it.

To get a list of tasks running in cmd we can run tasklist which details everything actively running on your machine. See How to kill a task via terminal on Windows

C:\Users\user> tasklist

Image Name                     PID Session Name        Session#    Mem Usage
========================= ======== ================ =========== ============
...
node.exe                      6736 Services                   0      2,080 K
cmd.exe                       3048 Services                   0      2,268 K
node.exe                      3664 Services                   0      6,768 K
...

Here, you can see that there are multiple node.exe programs running, but only one of them has the PID3664.

Stop the running process

Now that you know that it is3664 PID, you can commence putting an end to our runaway process. The general format is taskkill /f /pid ####, replacing the #### with the PID from above. If you try to run this without the /f flag, you'll most likely be prompted to use the /f Force flag by Windows.

C:\Users\user> taskkill /f /pid 3664
SUCCESS: The process with PID 3664 has been terminated.

And now you're set to start your process again!

Summary

• Find what Process ID (PID) is occupying the port in question with netstat -a -o -n

• (Optional) Confirm this PID is for the expected program with tasklist

• Terminate the process with taskkill /f /pid #### (replace #### with your PID)