Why a Daily Apps Script Trigger Suddenly Stops

Conclusion first: Over 80% of sudden trigger stops are caused by quota exhaustion, owner account auth invalidation, unhandled exceptions, or missing notifications. Implement a heartbeat sheet immediately and automate quota monitoring.

Checking Quota Limits

Permission and OAuth Scope Changes

Owner Account Security Events

Unhandled Exceptions and Silent Failures

Risks of Missing Notifications

Heartbeat Sheet Implementation

function heartbeat() {
  const ss = SpreadsheetApp.getActive();
  const sheet = ss.getSheetByName('heartbeat') || ss.insertSheet('heartbeat');
  sheet.appendRow([new Date(), Session.getActiveUser().getEmail()]);
}

Installable vs Simple Triggers Comparison

Item	Installable Trigger	Simple Trigger
Execution context	Owner account	Current user
Re-auth required	Frequent	Rare

Checklist:

• Check quota dashboard
• Test owner login
• Add try/catch + Logger.log

When Not to Use This Approach

See also: apps-script-automation-guide, six-minute-limit, retry-backoff, service-invoked-too-many-times, when-to-leave-gas

Final review criteria

The useful question is not how many features the automation has. It is whether the workflow can be understood, recovered, and safely rerun after something goes wrong.

• Raw input is separated from the human-facing working view.
• Each run records success, failure, processed count, and error message.
• Replaying the same input does not create duplicate results.
• Permission changes, quota errors, and external API failures are visible later.

For low-risk internal tasks, that may be enough. For customer replies, booking confirmation, inventory updates, payments, or legal records, the threshold is higher: compare Apps Script against a dedicated SaaS or a small server-backed system before relying on it.