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EventBridge rejects both day fields being set
ValidationException: Parameter ScheduleExpression is not valid.Why this happens
EventBridge, like Quartz, will not accept a value in both day fields. Exactly one must be ?.
Wrong and right
0 12 15 * MON *Our parser says: Use ? in exactly one of day-of-month and day-of-week
0 12 15 * ? *At 12:00 UTC, on the 15th of the month. First runs after 1 Jan 2027 (UTC): Fri 15 Jan, 12:00, Mon 15 Feb, 12:00, Mon 15 Mar, 12:00, Thu 15 Apr, 12:00, Sat 15 May, 12:00
How to fix it
- Choose a date or a weekday.
- Use ? in the other.
- For "first Monday" use the # form: 0 12 ? * 2#1 *.
The AWS EventBridge format at a glance
Fields in order: minute (0-59), hour (0-23), day-of-month (1-31), month (1-12), day-of-week (1-7, 1 = Sunday), year (1970-2199, required).
EventBridge rules always run in UTC. If you want a local time zone with DST support, use EventBridge Scheduler instead.
The fixed schedule in other systems
If you are moving this schedule to another scheduler, these are the equivalents of 0 12 15 * ? *:
| System | Expression |
|---|---|
| Quartz | 0 0 12 15 * ? |
| Spring | 0 0 12 15 * * |
| Crontab | 0 12 15 * * |
| Kubernetes | 0 12 15 * * |
| Jenkins | 0 12 15 * * |
| GitHub Actions | 0 12 15 * * |
| node-cron | 0 12 15 * * |
| Apache Airflow | 0 12 15 * * |
| Azure Functions | 0 0 12 15 * * |
| Google Cloud Scheduler | 0 12 15 * * |
Try it yourself
The tester below starts with the fixed expression. Change it and watch the schedule update.
Your week at a glance
Upcoming runs
| # | Local | UTC | From now |
|---|
Copy-ready code
Frequently asked questions
Why is the error so vague?
EventBridge returns the same message for any invalid expression, so check field count, ? and year first.
More AWS EventBridge fixes
See the full AWS EventBridge cron builder or convert between formats.