caddyserver/caddy · error

invalid IP address: '%s': %v

Error message

invalid IP address: '%s': %v

What it means

Error "invalid IP address: '%s': %v" thrown in caddyserver/caddy.

Source

Thrown at modules/caddyhttp/reverseproxy/reverseproxy.go:330

		mod, err := ctx.LoadModule(h, "DynamicUpstreamsRaw")
		if err != nil {
			return fmt.Errorf("loading upstream source module: %v", err)
		}
		h.DynamicUpstreams = mod.(UpstreamSource)
	}

	// parse trusted proxy CIDRs ahead of time
	for _, str := range h.TrustedProxies {
		if strings.Contains(str, "/") {
			ipNet, err := netip.ParsePrefix(str)
			if err != nil {
				return fmt.Errorf("parsing CIDR expression: '%s': %v", str, err)
			}
			h.trustedProxies = append(h.trustedProxies, ipNet)
		} else {
			ipAddr, err := netip.ParseAddr(str)
			if err != nil {
				return fmt.Errorf("invalid IP address: '%s': %v", str, err)
			}
			ipNew := netip.PrefixFrom(ipAddr, ipAddr.BitLen())
			h.trustedProxies = append(h.trustedProxies, ipNew)
		}
	}

	// ensure any embedded headers handler module gets provisioned
	// (see https://caddy.community/t/set-cookie-manipulation-in-reverse-proxy/7666?u=matt
	// for what happens if we forget to provision it)
	if h.Headers != nil {
		err := h.Headers.Provision(ctx)
		if err != nil {
			return fmt.Errorf("provisioning embedded headers handler: %v", err)
		}
	}

	if h.Rewrite != nil {
		err := h.Rewrite.Provision(ctx)

View on GitHub (pinned to 50e54ee279)

Solutions

1. Correct the IP address in the configuration; it must be a valid IPv4 or IPv6 address.

When it happens

Trigger: Thrown at modules/caddyhttp/reverseproxy/reverseproxy.go:330 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of caddyserver/caddy@50e54ee279 (2026-08-15). Data as JSON: /api/errors/07316a0b8779bd56. Report an issue: GitHub.