louislam/uptime-kuma · warning · Error

Ping timed out: "${line}"

Error message

Ping timed out: "${line}"

What it means

Thrown by parseTailscaleOutput() when a line of the tailscale ping output contains 'timed out'. This is the expected signal that the target Tailscale node did not respond to the ping within the CLI's window; the monitor treats it as a DOWN condition and relies on the scheduler to retry on the next interval.

Source

Thrown at server/monitor-types/tailscale-ping.js:62

    /**
     * Parses the output of the Tailscale ping command to update the heartbeat.
     * @param {string} tailscaleOutput The output of the Tailscale ping command.
     * @param {object} heartbeat The heartbeat object to update.
     * @returns {void}
     * @throws Will throw an eror if the output contains any unexpected string.
     */
    parseTailscaleOutput(tailscaleOutput, heartbeat) {
        let lines = tailscaleOutput.split("\n");

        for (let line of lines) {
            if (line.includes("pong from")) {
                heartbeat.status = UP;
                let time = line.split(" in ")[1].split(" ")[0];
                heartbeat.ping = parseInt(time);
                heartbeat.msg = "OK";
                break;
            } else if (line.includes("timed out")) {
                throw new Error(`Ping timed out: "${line}"`);
                // Immediately throws upon "timed out" message, the server is expected to re-call the check function
            } else if (line.includes("no matching peer")) {
                throw new Error(`Nonexistant or inaccessible due to ACLs: "${line}"`);
            } else if (line.includes("is local Tailscale IP")) {
                throw new Error(`Tailscale only works if used on other machines: "${line}"`);
            } else if (line !== "") {
                throw new Error(`Unexpected output: "${line}"`);
            }
        }
    }
}

module.exports = {
    TailscalePing,
};

View on GitHub (pinned to 6b5ea01557)

Solutions

1. Confirm the target machine is online and tailscaled is running on it ('tailscale status' on the source should show it).
2. Check 'tailscale status' for the peer's relay/direct status and 'tailscale netcheck' for local network conditions.
3. If persistent, review ACLs and firewall rules blocking UDP 41641 (or the configured port).
4. Treat transient timeouts as recoverable; the scheduler will retry on the next interval automatically.

function isTimeoutLine(line) { return typeof line === "string" && line.includes("timed out"); }

function isPongLine(line) { return typeof line === "string" && line.includes("pong from"); }

if (isTimeoutLine(line)) { heartbeat.status = DOWN; heartbeat.msg = `Ping timed out: "${line}"`; return; }

When it happens

Trigger: Produced when 'tailscale ping' reports a timeout line (e.g. 'pong from ... ' was not received and the output contains 'timed out'). The peer is reachable in the control plane but did not answer the DERP/direct ping in time.

Common situations: Target node offline or suspended; high latency or packet loss on the path; DERP relay congested and direct connection not established; target behind a restrictive firewall blocking WireGuard UDP; node in a tailnet that recently changed keysets.

Understand the failure class

• Timeouts: ETIMEDOUT, deadlines, and hung requests — what actually expires when a request times out.

Related errors

• Per-ping timeout must be between ${PING_PER_REQUEST_TIMEOUT_
• Timeout must be between ${PING_GLOBAL_TIMEOUT_MIN} and ${PIN
• Error checking Tailscale ping: ${err}
• Error in output: ${res.stderr.toString()}
• No output from Tailscale ping

AI-assisted analysis of louislam/uptime-kuma@6b5ea01557 (2026-08-12). Data as JSON: /api/errors/3a92533dc0b2e9c9. Report an issue: GitHub.