MySQL/PHP Error:[2002] Only one usage of each socket address (protocol/network address/port) is normally permitted

you can modify windows REGISTRY to fix that,

first in regedit open this path:

HKLM\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters

and create 4 new DWORD as this key and values:

TcpTimedWaitDelay
REG_DWORD: 0000001e (hex)

MaxUserPort
REG_DWORD: 0000fffe (hex)

TcpNumConnections
REG_DWORD: 00fffffe (hex)

TcpMaxDataRetransmissions
REG_DWORD: 00000005 (hex)

like with this screen shot:

reference

The error isn't actually coming from MySQL, but from Windows itself:

When a connection is closed, on the side that is closing the connection the 5 tuple { Protocol, Local IP, Local Port, Remote IP, Remote Port} goes into a TIME_WAIT state for 240 seconds by default.

In this case, the protocol is fixed - TCP

The local IP, remote IP and remote PORT are also typically fixed. So the variable is the local port.

What happens is that when you don't bind a port in the range 1024-5000 is used. So roughly you have 4000 ports. If you use all of them in 4 minutes - meaning roughly you make 16 web service calls per second for 4 minutes you will exhaust all the ports. That is the cause of this exception.

In other words, you've run out of ports in the dynamic range. That probably shouldn't be happening. How many concurrent users are you dealing with here?

The linked blog has workarounds:

1. Increase the dynamic port range through registry editing.
2. Reduce the time the system wants connections to spent in TIME_WAIT through registry editing.
3. Run a bit of code to do the above registry edit without regedit.

What a wide variety of workarounds!

See also this question on the Visual Studio forums, which explains:

The port will be locked for another minute or two to catch all packets which might have been sent before the application was terminated but haven't arrived yet. In Winsock API you can set socket option SO_REUSEADDR to resolve this (also this option can be set in .NET Socket class), but TcpListener is too high-level and doesn't let you set this option.

It's very likely that the underlying code to connect to MySQL or the code that handles connections in Apache isn't trying to use SO_REUSEADDR.

I'm going bet that your changing of the keepalive timeout had a direct impact here. Even though reducing it theoretically frees up the socket, Windows disagrees and keeps the socket reserved.

This is the Doldurma answer but for lazy people, you just have to place this inside a .reg file and than click it (reboot was not required in my case)

File content:

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters]

"TcpTimedWaitDelay"=dword:0000001e
"MaxUserPort"=dword:0000fffe
"TcpNumConnections"=dword:00fffffe
"TcpMaxDataRetransmissions"=dword:00000005

Happens to me when developing my Laravel projects. For developmental purposes, it's no biggie especially when you are using windows system. But for production, I simply run on Linux and problem solved. Also, change the MySQL connection from "localhost" to "127.0.0.1" if possible.