GitHub Actions: scheduled workflow not triggering [2026 fix]

CRON syntax errors or UTC timezone mismatches prevent scheduled GitHub Actions. Fix: validate CRON expression and ensure workflow file is on default branch.

GitHub Actions: Scheduled Workflow Not Triggering – 2am Incident Fix

TL;DR

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Real Error Messages You'll See

Check your GitHub Actions logs and settings for these exact errors:

``` Error: Invalid cron syntax in workflow file Schedule trigger is not valid cron expression ```

``` Warning: Scheduled workflow will not run No runs triggered for schedule event on this ref ```

``` Error parsing cron '@daily' is not supported Only standard cron syntax (5-field format) accepted ```

``` Workflow file not found on default branch Schedule event requires workflow on main/master branch ```

``` Error: Invalid day-of-week syntax Cron field 'day of week' must be 0-6 (0=Sunday) ```

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Broken Code vs. Fixed Code

Issue #1: Invalid CRON Syntax

BROKEN: ```yaml

.github/workflows/daily-deploy.yml

FIXED: ```yaml

.github/workflows/daily-deploy.yml

Why it broke: The syntax *looks* correct but GitHub Actions runs validation when you push. The workflow file must be committed to your default branch before the schedule is registered. If you edited it locally without pushing, no schedule exists yet.

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Issue #2: Workflow File on Wrong Branch

BROKEN: ```bash

You created the workflow on a feature branch

Workflow never runs because it's not on main/master!

FIXED: ```bash

Commit to your default branch (main or master)

Now GitHub detects the schedule and registers it

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Issue #3: Invalid Day-of-Week Field

BROKEN: ```yaml on: schedule: - cron: '0 2 * * mon' # GitHub doesn't accept 3-letter day names ```

FIXED: ```yaml on: schedule: - cron: '0 2 * * 1' # Monday is 1 (0=Sunday, 6=Saturday) ```

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Issue #4: @daily Shorthand (Not Supported)

BROKEN: ```yaml on: schedule: - cron: '@daily' # GitHub Actions doesn't support shorthand ```

FIXED: ```yaml on: schedule: - cron: '0 0 * * *' # Equivalent: 00:00 UTC every day ```

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Verification Checklist

1. Validate CRON syntax at [crontab.guru](https://crontab.guru) before deploying - Format: minute hour day month day-of-week (5 fields, space-separated) - All fields required; no shorthand (@daily, @weekly, etc.)

2. Confirm file on default branch: ```bash git log --oneline -- .github/workflows/YOUR_FILE.yml # Should show commits on main/master, not feature branches ```

3. Check GitHub UI: Settings → Actions → General → Check that your workflow appears in the "Workflows" list (proves it's detected)

4. Review timezone: Cron times in GitHub Actions are always UTC. If you want 2 AM EST, use cron: '0 7 * * *' (EST is UTC-5, so 7 AM UTC = 2 AM EST)

5. Wait 5 minutes: GitHub caches schedule registrations. After pushing, wait a few minutes before checking if the schedule registered.

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Still broken? Check these too

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Related Troubleshooting

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Official Documentation

[GitHub Actions: Scheduled events (schedule)](https://docs.github.com/en/actions/using-workflows/events-that-trigger-workflows#schedule)

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Version Notes

I'm certain about the 5-field CRON requirement and default branch requirement as of 2026—these are fundamental GitHub Actions constraints. However, GitHub may have added shorthand support (@daily, @weekly) in newer API versions; if you're on the latest Actions runner and @daily works for you, drop a comment.

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Found a different variation? Drop it in the comments—we update this guide based on your 2am fire stories.