Event Grid message delivery and retry

This article describes how Azure Event Grid handles events when delivery is not acknowledged.

Event Grid provides durable delivery. It delivers each message at least once for each subscription. Events are sent to the registered webhook of each subscription immediately. If a webhook does not acknowledge receipt of an event within 60 seconds of the first delivery attempt, Event Grid retries delivery of the event.

Message delivery status

Event Grid uses HTTP response codes to acknowledge receipt of events.

Success codes

The following HTTP response codes indicate that an event has been delivered successfully to your webhook. Event Grid considers delivery complete.

  • 200 OK
  • 202 Accepted

Failure codes

The following HTTP response codes indicate that an event delivery attempt failed. Event Grid tries again to send the event.

  • 400 Bad Request
  • 401 Unauthorized
  • 404 Not Found
  • 408 Request timeout
  • 414 URI Too Long
  • 500 Internal Server Error
  • 503 Service Unavailable
  • 504 Gateway Timeout

Any other response code or a lack of a response indicates a failure. Event Grid retries delivery.

Retry intervals

Event Grid uses an exponential backoff retry policy for event delivery. If your webhook does not respond or returns a failure code, Event Grid retries delivery on the following schedule:

  1. 10 seconds
  2. 30 seconds
  3. 1 minute
  4. 5 minutes
  5. 10 minutes
  6. 30 minutes
  7. 1 hour

Event Grid adds a small randomization to all retry intervals.

Retry duration

During the preview, Azure Event Grid expires all events that are not delivered within two hours. Before General Availability, this time will be increased to 24 hours.

Next steps