tailscale/tailscale · error

connecting to system bus: %w

Error message

connecting to system bus: %w

What it means

nmManager.SetDNS retries trySet every 10ms until reconfigTimeout; each trySet starts with dbus.SystemBus() to reach NetworkManager. This error means the D-Bus system bus connection itself failed: no system bus daemon running, the socket path wrong, or access denied. The wrapped error from go.dbus carries the underlying cause.

Source

Thrown at net/dns/nm.go:82

	// configured before the DNS manager was invoked, but it might
	// take a little time for the netlink notifications to propagate
	// up. So, keep retrying for the duration of the reconfigTimeout.
	var err error
	for ctx.Err() == nil {
		err = m.trySet(ctx, config)
		if err == nil {
			break
		}
		time.Sleep(10 * time.Millisecond)
	}

	return err
}

func (m *nmManager) trySet(ctx context.Context, config OSConfig) error {
	conn, err := dbus.SystemBus()
	if err != nil {
		return fmt.Errorf("connecting to system bus: %w", err)
	}

	// This is how we get at the DNS settings:
	//
	//               org.freedesktop.NetworkManager
	//                              |
	//                    [GetDeviceByIpIface]
	//                              |
	//                              v
	//           org.freedesktop.NetworkManager.Device <--------\
	//              (describes a network interface)             |
	//                              |                           |
	//                   [GetAppliedConnection]             [Reapply]
	//                              |                           |
	//                              v                           |
	//          org.freedesktop.NetworkManager.Connection       |
	//                   (connection settings)            ------/
	//          contains {dns, dns-priority, dns-search}

View on GitHub (pinned to 6e0912f979)

Solutions

1. Start and enable the bus and NM: `systemctl enable --now dbus NetworkManager`.
2. Check the socket: `ls -l /run/dbus/system_bus_socket` and `busctl --system` to confirm connectivity.
3. Inspect DBUS_SYSTEM_BUS_ADDRESS in the tailscaled environment and unset it if wrong.
4. If D-Bus truly cannot run on this host, select a different DNS manager (e.g. direct resolv.conf) instead of the NetworkManager one.

// Probe the system bus before depending on the NetworkManager manager
conn, err := dbus.SystemBus()
if err != nil {
    return nil, fmt.Errorf("system dbus unavailable, cannot use NetworkManager DNS: %w", err)
}
defer conn.Close()

Retry SetDNS with backoff — dbus availability at boot is ordering-dependent, and SetDNS's internal loop already retries until reconfigTimeout; persistent failure means an environment problem, so surface 'start dbus' to the operator.

When it happens

Trigger: trySet calls dbus.SystemBus() and it returns an error: /run/dbus/system_bus_socket missing, dbus-daemon not running, DBUS_SYSTEM_BUS_ADDRESS pointing somewhere invalid, or the process lacks permission to connect to the socket.

Common situations: Minimal containers or chroots without D-Bus; dbus.service failed or masked while NetworkManager appears installed; tailscaled started before dbus at boot; DBUS_SYSTEM_BUS_ADDRESS set incorrectly in the unit Environment.

Related errors

• checking NetworkManager version: %v
• getDeviceByIpIface: %w
• getAppliedConnection: %w
• reapply: %w
• unexpected NM config type %T

AI-assisted analysis of tailscale/tailscale@6e0912f979 (2026-08-18). Data as JSON: /api/errors/f00a2fb1549c9c15. Report an issue: GitHub.