caddyserver/caddy · error

multiple ports not supported

Error message

multiple ports not supported

What it means

NetWriter opens exactly one connection, so Provision rejects addresses whose PortRangeSize() != 1. A port range like 'tcp/host:5000-5010' spans multiple ports and cannot map to a single dial target for a log writer.

Source

Thrown at modules/logging/netwriter.go:73

		New: func() caddy.Module { return new(NetWriter) },
	}
}

// Provision sets up the module.
func (nw *NetWriter) Provision(ctx caddy.Context) error {
	repl := caddy.NewReplacer()
	address, err := repl.ReplaceOrErr(nw.Address, true, true)
	if err != nil {
		return fmt.Errorf("invalid host in address: %v", err)
	}

	nw.addr, err = caddy.ParseNetworkAddress(address)
	if err != nil {
		return fmt.Errorf("parsing network address '%s': %v", address, err)
	}

	if nw.addr.PortRangeSize() != 1 {
		return fmt.Errorf("multiple ports not supported")
	}

	if nw.DialTimeout < 0 {
		return fmt.Errorf("timeout cannot be less than 0")
	}

	return nil
}

func (nw NetWriter) String() string {
	return nw.addr.String()
}

// WriterKey returns a unique key representing this nw.
func (nw NetWriter) WriterKey() string {
	return nw.addr.String()
}

View on GitHub (pinned to 50e54ee279)

Solutions

1. Change the address to a single port, e.g. 'tcp/logs.example.com:2000'
2. If you need multiple destinations, configure several log outputs or a relay instead of a range

Example fix

# before
output net tcp/logs.example.com:2000-2010

# after
output net tcp/logs.example.com:2000

if a, err := caddy.ParseNetworkAddress(addr); err == nil && a.PortRangeSize() != 1 {
    return fmt.Errorf("net output requires a single port, got range %s", a.String())
}

When it happens

Trigger: Configuring output net with a port range, e.g. 'net tcp/logs.example.com:2000-2010' or a placeholder expanding to a range.

Common situations: Copy-pasting listener address syntax (where ranges are legal) into an output address; templated configs that append ':1000-1010'.

Related errors

• invalid host in address: %v
• parsing network address '%s': %v
• timeout cannot be less than 0
• must be exactly one listener address; cannot listen on: %s
• download failed: %v

AI-assisted analysis of caddyserver/caddy@50e54ee279 (2026-08-15). Data as JSON: /api/errors/3faae39a5fc387f6. Report an issue: GitHub.