Monitor silent n8n workflow failures with Slack, email and Google Sheets

Quick overview

This workflow monitors selected n8n workflows via the n8n public API to detect “silent failures” such as empty successful runs, missed schedules, switched-off workflows, and missing expected records, then sends alerts to Slack and email and logs findings to Google Sheets.

How it works

1. Runs every 15 minutes to check watched workflows, sends a daily Slack summary at 8am, and also supports a manual test run with sample data.
2. Reads your monitoring configuration, including the n8n base URL and a JSON list of workflows to check and their thresholds.
3. For each configured workflow, calls the n8n API to fetch the workflow status (active/inactive) and its recent executions, and optionally calls a separate “record check” URL to count expected records.
4. Evaluates recent executions to flag empty successful runs (too few items past a specified step), missed schedules (no execution within the allowed gap), inactive workflows, missing records at the check URL, and optionally failed runs.
5. Deduplicates findings so each unique problem is only reported once, while also tracking check activity for the daily summary.
6. Sends a bundled alert to Slack and an email with links to the affected workflows/executions, and appends each finding as a new row in a Google Sheets log.

Setup

1. Enable the n8n public API, create an n8n API key, and add an HTTP Header Auth credential (for example X-N8N-API-KEY) for the n8n API requests.
2. Update the Config values, especially n8n_base_url, slack_webhook_url, alert_email, from_email, lookback_hours, and checks_json with your real workflow IDs, node names to count, and schedule/record thresholds.
3. Create a Slack incoming webhook and add its URL to the Config.
4. Configure an SMTP email credential for the email alert step.
5. Connect Google Sheets OAuth credentials, set the target spreadsheet ID, and ensure it has a tab named “Silent failures” for appending log rows.