Event Processor Client - Invalid Offset Error

@Neeraj Mahajan

Thanks for using Microsoft Q&A forum and posting your query.

The "invalid offset" error you're encountering with the Azure Event Hubs EventProcessorClient typically occurs when the client attempts to read from an offset that no longer exists in the Event Hub. This can happen for several reasons, and I’ll provide some potential causes

Retention Policy: If the offset you’re trying to use is outside the retention period of the Event Hub, it will be considered invalid. Ensure that the offset falls within the retention period of your Event Hub.

Blob Storage Checkpointing: Even after deleting the consumer group information from Blob Storage, there might be residual data causing the issue. Make sure to:

• Stop the EventProcessorClient.
• Delete the entire folder related to the consumer group in Blob Storage.
• Restart the EventProcessorClient.

Event Hub Recreation: If the Event Hub was recreated with the same name, it might cause offset issues. Ensure that the Event Hub and its associated resources are correctly configured and not conflicting with previous instances1.

Cache or Metadata: There might be cached metadata or other underlying system data causing the issue. Try the following:

• Clear any local caches or metadata related to the Event Hub.
• Ensure that no other instances of EventProcessorClient are running with conflicting configurations.

Recommendations for Prevention

Regular Checkpointing: Ensure that your application regularly checkpoints offsets to avoid large gaps that might fall outside the retention period.

1. Error Handling: Implement robust error handling in your EventProcessorClient to catch and handle invalid offset errors gracefully. You can use the ProcessErrorAsync event to handle such errors and reset the offset if necessary
2. Monitoring and Alerts: Set up monitoring and alerts for your Event Hub to catch issues early. Use tools like Azure Monitor and Application Insights to track the health and performance of your Event Hub.
3. Documentation and Best Practices: Follow Azure’s best practices for Event Hubs and keep your documentation up to date. This includes understanding the retention policies, checkpointing strategies, and error handling mechanisms

By addressing these areas, you should be able to resolve the invalid offset error and prevent it from occurring in the future. If the issue persists, please do let us know.

please refer

1: GitHub Issue on Event Hub Offset Errors

3: EventProcessorClient Class Documentation

https://stackoverflow.com/questions/76791517/event-hub-source-connector-throwing-invalid-offset-error-after-changing-event

Hope this helps. Do let us know if you any further queries.

@Neeraj Mahajan We haven’t heard from you on the last response and was just checking back to see if you have a resolution yet. In case if you have any resolution please do share that same with the community as it can be helpful to others. Otherwise, will respond with more details and we will try to help.

@phemanth Thank you for your reply. I ended up deleting the entire consumer group folder from the blob storage, and redeploying the EventProcessorClient resolved the issue for me. My consumer group folder was created again in the blob after successfully running. I had originally hosted EventProcessorClient as a background service in a container app, so it’s possible that some configurations were causing the issue. I appreciate your recommendations—thanks again!