AWS SDK for .NET Documentation
UnprocessedItems Property
AmazonAmazon.DynamoDB.ModelBatchWriteItemResultUnprocessedItems Did this page help you?   Yes   No    Tell us about it...
The Items which we could not successfully process in a BatchWriteItem call is returned as UnprocessedItems

Constraints:

Length
1 - 25

Declaration Syntax
C#
public Dictionary<string, List<WriteRequest>> UnprocessedItems { get; set; }

Assembly: AWSSDK (Module: AWSSDK) Version: 1.5.60.0 (1.5.60.0)