louislam/uptime-kuma · error · Error

Conditions not met - Topic: ${messageTopic}; Message: ${rece

Error message

Conditions not met - Topic: ${messageTopic}; Message: ${receivedMessage}

What it means

Thrown by MqttMonitorType.checkConditions when evaluateExpressionGroup returns false for the condition data {topic, message, json_value}. This is the conditions-system path; the message body and topic are exposed to user-defined operators, and json_value is the stringified JSONata result (empty string when jsonPath is unset or JSON parsing failed silently).

Source

Thrown at server/monitor-types/mqtt.js:125

                jsonValue = await expression.evaluate(parsedMessage);
            } catch (e) {
                // JSON parsing failed, jsonValue remains null
            }
        }

        const conditionData = {
            topic: messageTopic,
            message: receivedMessage,
            json_value: jsonValue?.toString() ?? "",
        };

        const conditionsResult = evaluateExpressionGroup(conditions, conditionData);

        if (conditionsResult) {
            heartbeat.msg = `Topic: ${messageTopic}; Message: ${receivedMessage}`;
            heartbeat.status = UP;
        } else {
            throw new Error(`Conditions not met - Topic: ${messageTopic}; Message: ${receivedMessage}`);
        }
    }

    /**
     * Connect to MQTT Broker, subscribe to topic and receive message as String
     * @param {string} hostname Hostname / address of machine to test
     * @param {string} topic MQTT topic
     * @param {object} options MQTT options. Contains port, username,
     * password, websocketPath and interval (interval defaults to 20)
     * @returns {Promise<string>} Received MQTT message
     */
    mqttAsync(hostname, topic, options = {}) {
        return new Promise((resolve, reject) => {
            const { port, username, password, websocketPath, interval = 20 } = options;

            // Adds MQTT protocol to the hostname if not already present
            if (!/^(?:http|mqtt|ws)s?:\/\//.test(hostname)) {
                hostname = "mqtt://" + hostname;

View on GitHub (pinned to 6b5ea01557)

Solutions

1. Confirm the published payload is valid JSON when monitor.jsonPath is set (a non-JSON payload silently blanks json_value).
2. Verify the condition references only exposed variables: 'topic', 'message', 'json_value'.
3. Test the condition expression against the actual topic/message/json_value triple using evaluateExpressionGroup directly.
4. If matching raw text, use the 'message' variable with the right string operator; switch json_value conditions to 'message' contains if JSON is unreliable.

Example fix

// before: condition variable='value' operator='==' value='ON'  (no such variable)
// after:  condition variable='json_value' operator='==' value='ON'
// and ensure payload is JSON {"state":"ON"} so json_value is populated

const { evaluateExpressionGroup } = require('../server/monitor-conditions/evaluator');
function dryRunConditions(group, topic, message, jsonValue) {
  return evaluateExpressionGroup(group, { topic, message, json_value: jsonValue ?? '' });
}

function conditionsExposeOnlyAllowedVars(group) {
  const allowed = new Set(['topic','message','json_value']);
  return group.children.every(c => allowed.has(c.variable));
}

try { await mqttMonitor.checkConditions(monitor, heartbeat, topic, msg, group); }
catch (e) { if (/Conditions not met/.test(e.message)) { heartbeat.status = DOWN; heartbeat.msg = e.message; } else throw e; }

When it happens

Trigger: monitor.conditions parses to a non-empty ConditionExpressionGroup (hasConditions true), mqttAsync resolves with a message, and the evaluated group over {topic, message, json_value} is false. Also fires when monitor.jsonPath is set but receivedMessage is not valid JSON — the inner try/catch swallows the parse error, json_value becomes '', and conditions referencing json_value then fail.

Common situations: Condition uses the wrong variable name (e.g. 'value' instead of 'json_value'); operator chosen expects a number but json_value is empty because JSON parse failed; regex/case-sensitive string operator against a differently-cased payload; jsonPath typo producing empty json_value.

Related errors

• Message Mismatch - Topic: ${monitor.mqttTopic}; Message: ${r
• Message received but value is not equal to expected value, v
• Service Name is required.
• Invalid service name. Please use the internal Service Name (
• Invalid PM2 process name.

AI-assisted analysis of louislam/uptime-kuma@6b5ea01557 (2026-08-12). Data as JSON: /api/errors/4c8c56eeae6cdb48. Report an issue: GitHub.