There are a variety of reasons a custom monitor may fail to run, such as a query time-out, insufficient permissions, or a referenced table being deleted.
When configuring a custom monitor, you have the option to be proactively notified when that monitor fails.
To enable Failure Notifications for a monitor, go to the Send Notifications section of the monitor creation or edit wizard, and switch the toggle to the right (purple).
If the monitor fails while this option is enabled, a failure notification will be sent to same destinations that an Incident notification would be sent to.
Failure notifications are currently batched on a 12 hour schedule. This is to avoid sending excessive alerts if a high-frequency rule is failing repeatedly.
Updated about 1 month ago