EC
net.ErrClosed
GoERRORNotableNetwork

use of closed network connection

Quick Answer

Use errors.Is(err, net.ErrClosed) to detect closed-connection errors in server accept loops.

What this means

Returned when a network operation is attempted on a connection that has already been closed. Often surfaces as a wrapped error string.

Why it happens
  1. 1Listener or connection closed while a goroutine is still blocking on it
  2. 2Graceful shutdown closing the listener before accept loop exits

Fix

Check in accept loop

Check in accept loop
if errors.Is(err, net.ErrClosed) {
    return // listener intentionally closed
}
log.Println("accept error:", err)

Why this works

Returning on net.ErrClosed allows clean shutdown without spurious error logs.

Code examples
Detect in accept loopgo
conn, err := ln.Accept()
if errors.Is(err, net.ErrClosed) {
    return
}
Close listener on quitgo
go func() {
    <-quit
    ln.Close()
}()
Wrap checkgo
if err != nil && !errors.Is(err, net.ErrClosed) {
    log.Fatal(err)
}
Sources
Official documentation ↗

Go standard library

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