How to fix TrimmedDataAccessException: The requested data has been trimmed in DynamoDB

Describe the stream and inspect RetentionPeriodHours plus the shard iterator you are using:

https://docs.aws.amazon.com/cli/latest/reference/dynamodbstreams/describe-stream.html#examples

1. Run aws dynamodbstreams describe-stream --stream-arn <arn> to read RetentionPeriodHours. The default is 24 hours.
2. Compare the iterator type you request (AT_SEQUENCE_NUMBER, AT_TIMESTAMP, TRIM_HORIZON, LATEST) with the sequence number stored in the checkpoint.
3. If you are using AT_SEQUENCE_NUMBER or a saved checkpoint, verify the sequence number is within the last 24 hours; anything older has been trimmed and cannot be read.

When the iterator has been trimmed, lesion handler must skip ahead to a fresh position:

1. Use TRIM_HORIZON (to replay everything still in retention) or LATEST (to start from the newest data) instead of the stale shard iterator.
2. Alternatively, call GetShardIterator with AT_TIMESTAMP and a timestamp that is now minus the retention window to jump just before the oldest available record.
3. For Kinesis Client Library consumers, clear the checkpoint for the affected shard (the ~cl table) so it reinitializes using a new iterator and not an expired sequence number.

This ensures the next GetRecords request points to a record that still exists inside DynamoDB Streams’ trim horizon.

Catch TrimmedDataAccessException and treat it as a signal to reset your checkpoint instead of retrying the same iterator:

npm install @aws-sdk/client-dynamodb-streams

switch (error.name) {
case 'TrimmedDataAccessException':
// log the event, optionally notify, then reset the shard iterator
await resetCheckpointShard(/* shardId */);
continue; // or break and restart consumer loop
default:
throw error;
}

Add alerts on repeated TrimmedDataAccessException spikes and monitor GetRecords error metrics. If consumers regularly fall behind hopes beyond 24 hours, consider increasing the stream retention window (up to 7 days) or keeping the application online longer.