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WSAENOBUFS: 10055: No buffer space available.



The WSAENOBUFS is returned because you are calling a port that was recently used and has not yet been released.  If you try to use a TCP port that is already in use, the operating system (OS) will trigger an error, but not because the OS is behaving improperly, but just to warn that the APPLICATION making use of the OS sys call is trying to do something that is incorrect: you cannot bind two different applications to the same TCP port.

The registry parameter MaxUserPort needs to be set..

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters On the Edit menu, click New, and then add the following registry entry then reboot Windows.

Value Name: MaxUserPort Value Type: DWORD Value data: 65534 Valid Range: 5000-65534 (decimal).

Microsoft documentation about this is available at:



By default, a TCP port remains locked for 240 seconds (that is, four minutes) after the connection is closed. You can also adjust this within a range of 10 to 300 seconds.  The key name is:

    o  HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\TcpTimedWaitDelay Please set to 10 seconds and reboot Windows..

Microsoft documentation about this is available at:


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