Tcp port is already in use.How do I check if a port is already in use?

Question: SQL Server won't start , so checked Event Viewer and getting the following message. 

Server TCP provider failed to listen on [ 'any' <ipv4> 50010]. Tcp port is already in use.

How can I check if the port is already in use and which other process or service  has locked the port and therefore not allowing SQL Server to start on designated port ?

Answer:

The  first thing to identify is the Owning process and check the Process Name . There are different methods to list the processes currently using (or not using) the port. 

I like using Powershell for investing Windows related issues . Here is a Powershell script that  will either return the : Local Address, Local Port ,Remote Address,Remote Port ,State ,Applied Setting , Owning Process 

or if there are no processes utilising the port - return a  message 

The TCP connections are returned by the Get-NetTCPConnection powershell cmdlet. 

cls
$TcpPort = "50010"
$TcpConn = Get-NetTCPConnection | Where-Object {$_.LocalPort -eq $TcpPort -or $_.RemotePort -eq $TcpPort}
$TcpConn
$process = $TcpConn | Select-Object OwningProcess -Unique
if ($process -ne $null)
{
    Get-Process | Where-Object {$_.id -eq $process.OwningProcess} | Select-Object Id, ProcessName
}
else
{
    write-output "No services\processes discovered using the port"
}

read more on ports 

How to find SQL Server tcp port with Powershell

How to find the local tcp port used on SQL Server

Change the port for sql server service broker

How to get SQL port number using xp_readererrorlog

How to configure SQL Server static port with Powershell