# Expired iterator exception errors
<a name="kinesis-fis-expired-iterator"></a>

 Expired iterator exception errors (HTTP 400) occur when the shard iterator is expired, and is no longer used to retrieve stream records when calling `GetRecords`. This occurs when there are delays between read operations, which are caused by long-running data processing tasks, network issues, or application downtime. 

**Note**  
A shard iterator is valid for 5 minutes after the time it's issued.

**Recommendations for handling exceptions**
+ Refreshing shard iterators before they expire.
+ Incorporating error handling to obtain new iterators.
+ Utilizing the Kinesis Kinesis Client Library (KCL) which automatically manages shard iterator expiration.

For more information, see [What is AWS Fault Injection Service?](https://docs.aws.amazon.com/fis/latest/userguide/what-is.html)

**To perform a basic experiment**

1. Create an experiment template: use the AWS FIS console. 

1. Select the action: use the `aws:kinesis:inject-api-expired-iterator-exception` action.

1. Configure the targets: specify the IAM role and Kinesis Data Streamsoperations. 

1. Set the duration: start with 5-10 minutes for initial testing. 

1. Add stop conditions: [stop conditions for AWS FIS](https://docs.aws.amazon.com/fis/latest/userguide/stop-conditions.html).

1. Run the experiment: monitor the application behavior.

**Action details**
+ **Resource Type**: IAM Role ARN
+ **Target Operations**: `GetRecords`
+ ****Error Code****: `ExpiredIteratorException`(HTTP 400)
+ ****Description****: the provided iterator exceeds the maximum age allowed, simulating scenarios where record processing is too slow or checkpointing logic fails.

**Parameters**
+ **IAM Role ARN**: the role that your application uses for Kinesis Data Streams operations.
+ **Operations**: target operations: `GetRecords`
+ **Resource List**: the specific stream names or ARNs.
+ **Duration**: the experiment duration. This is configurable. 
+ **Intensity**: the percentage of requests to throttle.

**Required permissions**
+ `kinesis:InjectApiError`