XTLS/Xray-core · error

No available name server could be created from

Error message

No available name server could be created from 

What it means

The peer's padding record length (decoded varint) is rejected by readPaddingTurn when it is smaller than its own header length or exceeds maxPaddingTurnLength (8 MiB). This guards against absurd allocations and detects peers speaking a different or corrupted protocol: a legit record is always at least headerLength bytes and at most 8 MiB.

Source

Thrown at app/dns/nameserver.go:87

			return NewTCPLocalNameServer(u, disableCache, serveStale, serveExpiredTTL, clientIP)
		case strings.EqualFold(u.String(), "fakedns"):
			var fd dns.FakeDNSEngine
			err = core.RequireFeatures(ctx, func(fdns dns.FakeDNSEngine) {
				fd = fdns
			})
			if err != nil {
				return nil, err
			}
			return NewFakeDNSServer(fd), nil
		}
	}
	if dest.Network == net.Network_Unknown {
		dest.Network = net.Network_UDP
	}
	if dest.Network == net.Network_UDP { // UDP classic DNS mode
		return NewClassicNameServer(dest, dispatcher, disableCache, serveStale, serveExpiredTTL, clientIP), nil
	}
	return nil, errors.New("No available name server could be created from ", dest).AtWarning()
}

// NewClient creates a DNS client managing a name server with client IP, domain rules and expected IPs.
func NewClient(
	ctx context.Context,
	ns *NameServer,
	clientIP net.IP,
	disableCache bool, serveStale bool, serveExpiredTTL uint32,
	tag string,
	ipOption dns.IPOption,
	updateRules func(bool),
) (*Client, error) {
	client := &Client{}
	err := core.RequireFeatures(ctx, func(dispatcher routing.Dispatcher) error {
		// Create a new server for each client for now
		server, err := NewServer(ctx, ns.Address.AsDestination(), dispatcher, disableCache, serveStale, serveExpiredTTL, clientIP)
		if err != nil {
			return errors.New("failed to create nameserver").Base(err).AtWarning()

View on GitHub (pinned to 7d214f8b09)

Solutions

1. Confirm the remote address actually serves the XMC transport with padding enabled
2. Align client/server versions so maxPaddingTurnLength matches on both ends
3. Treat as fatal for the connection; reconnect and re-run the schedule

if err != nil && strings.Contains(err.Error(), "invalid padding record length") {
    // almost certainly not an XMC padding peer or a corrupted stream; abort and alert
}

When it happens

Trigger: Connecting to a service that is not an XMC padding peer (its first bytes decode to a huge varint); stream corruption mid-handshake; a forked peer with a different max turn length.

Common situations: Wrong inbound port behind a reverse proxy pointing at a plain HTTP/TLS backend; version skew where one side allows > 8 MiB turns; bit-level corruption on flaky links.

Related errors

• not a Service.
• Dispatcher: Invalid destination.
• FakeDNSEngine is not initialized, but such a sniffer is used
• Failed to convert address to Net IP.
• unexpected client IP length

AI-assisted analysis of XTLS/Xray-core@7d214f8b09 (2026-08-15). Data as JSON: /api/errors/a9ac767bb603b1c0. Report an issue: GitHub.