louislam/uptime-kuma · error · Error

Invalid JSON in database query: ${error.message}

Error message

Invalid JSON in database query: ${error.message}

What it means

Thrown by Monitor.validate() for type "mongodb" when databaseQuery is set and JSON.parse fails. The query is stored as a JSON string and later parsed by the MongoDB monitor to build a find/aggregation call, so malformed JSON would crash at check time.

Source

Thrown at server/model/monitor.js:1777

                const maxDelayFromTimeout = this.interval * 1000 * 0.8;
                if (delay >= maxDelayFromTimeout) {
                    throw new Error(`Screenshot delay must be less than ${maxDelayFromTimeout}ms (0.8 × interval)`);
                }

                // Must not exceed 0.5 * interval to prevent blocking next check
                const maxDelayFromInterval = this.interval * 1000 * 0.5;
                if (delay >= maxDelayFromInterval) {
                    throw new Error(`Screenshot delay must be less than ${maxDelayFromInterval}ms (0.5 × interval)`);
                }
            }
        }

        if (this.type === "mongodb" && this.databaseQuery) {
            // Validate that databaseQuery is valid JSON
            try {
                JSON.parse(this.databaseQuery);
            } catch (error) {
                throw new Error(`Invalid JSON in database query: ${error.message}`);
            }
        }
    }

    /**
     * Gets monitor notification of multiple monitor
     * @param {Array} monitorIDs IDs of monitor to get
     * @returns {Promise<LooseObject<any>>} object
     */
    static async getMonitorNotification(monitorIDs) {
        return await R.getAll(
            `
            SELECT monitor_notification.monitor_id, monitor_notification.notification_id
            FROM monitor_notification
            WHERE monitor_notification.monitor_id IN (${monitorIDs.map((_) => "?").join(",")})
        `,
            monitorIDs
        );

View on GitHub (pinned to 6b5ea01557)

Solutions

1. Write strict JSON: double-quoted keys, no trailing commas, no comments, e.g. "{ "limit": 1, "sort": { "_id": -1 } }".
2. Validate the string with a JSON linter or JSON.parse before submitting.
3. If you need shell-only syntax, convert it to JSON first using a tool such as `mongo --eval` to canonicalize.

Example fix

// before
{ type: "mongodb", databaseQuery: "{ limit: 1, }" }
// after
{ type: "mongodb", databaseQuery: "{ \"limit\": 1 }" }

function validMongoQuery(q) {
  if (!q) return true;
  try { JSON.parse(q); return true; } catch { return false; }
}

function isJsonString(v) {
  if (typeof v !== "string" || v.length === 0) return v == null;
  try { JSON.parse(v); return true; } catch { return false; }
}

try {
  await bean.validate();
} catch (e) {
  if (/Invalid JSON in database query/.test(e.message)) return badRequest("databaseQuery must be strict JSON");
  throw e;
}

When it happens

Trigger: Save a mongodb monitor with databaseQuery containing trailing commas, single quotes, unquoted keys, comments, or unescaped characters. e.g. "{ limit: 1, }" or "{'field': 1}".

Common situations: User pastes a Mongo shell expression (JS object literal) instead of strict JSON. Editing the query in a text editor that auto-inserts smart quotes. Copying from MongoDB Compass which may emit shell syntax.

Understand the failure class

• Parsing and encoding errors: unexpected token, malformed input — why parsers reject input and how to find the real culprit.

Related errors

• Service Name is required.
• Invalid service name. Please use the internal Service Name (
• Invalid PM2 process name.
• Packet size must be between ${PING_PACKET_SIZE_MIN} and ${PI
• Per-ping timeout must be between ${PING_PER_REQUEST_TIMEOUT_

AI-assisted analysis of louislam/uptime-kuma@6b5ea01557 (2026-08-12). Data as JSON: /api/errors/8f823f8c3199b644. Report an issue: GitHub.