Socket persists in Golang

connectex: Only one usage of each socket address (protocol/network address/port) is normally permitted.Client message: panic: runtime error: invalid memory address or nil pointer dereference
[signal 0xc0000005 code=0x0 addr=0x18 pc=0x49a69e]

goroutine 1 [running]:
fmt.Fprintf(0x0, 0x0, 0xc0005a1bd0, 0xc, 0x0, 0x0, 0x0, 0xc000094280, 0x20, 0x0)
        C:/Go/src/fmt/print.go:189 +0x7e

I was stress testing my server and I found this problem after a lot of queries to the server. It seems that the connection persists sometimes not allowing the socket to make another connection. If thats not the problem can someone explain it to me? Also provide/lead me to a solution?

Thanks!