MuleSoft S3 Connector "On New Object" Does Not Return All Events in a Single Polling Cycle

Publish Date: Jun 9, 2026

Description

When using the MuleSoft Amazon S3 Connector's "On New Object" source operation, new objects may be returned across multiple polling cycles rather than all at once.

Example Behavior

When 11 files are uploaded to an S3 bucket within 1 second with a 10-second polling interval configured in MuleSoft, objects may be returned as follows:

---
13:06:17 --- 3 objects
13:06:27 --- 2 objects
13:06:37 --- 2 objects
13:06:47 --- 2 objects
13:06:57 --- 1 object
13:07:07 --- 1 object
---

As shown above, all 11 objects are not returned in the first polling cycle.

Cause

The MuleSoft Amazon S3 Connector's "On New Object" source operation relies on AWS SQS (Simple Queue Service) to receive S3 event notifications. Due to its distributed architecture, AWS SQS does not guarantee that all available messages are returned in a single retrieval. This is a known characteristic of AWS SQS and does not result in message loss — all events are eventually delivered and processed (see [1-2]).

Resolution

This behavior is currently by design.
Mitigation is to adjust the poll interval (see [3]) in your MuleSoft application to check the queue more frequently.

Reference

[1] https://docs.aws.amazon.com/AWSSimpleQueueService/latest/SQSDeveloperGuide/sqs-short-and-long-polling.html
[2] https://repost.aws/questions/QUSFyO7uCNQ3a2FLyepHoJqg/some-messages-are-being-polled-others-are-missed-in-aws-sqs
[3] On New Object - Scheduling Strategy

Additional Resources

If retrieving all events in a single polling cycle is a critical requirement, please submit an Idea Exchange (https://ideas.salesforce.com/s/) request asking for the MuleSoft S3 Connector to support returning all messages in one polling cycle.

Knowledge Article Number

005386545

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