Topic Status: Some information in this topic is preview and subject to change in future releases. Preview information describes new features or changes to existing features in Microsoft SQL Server 2016 Community Technology Preview 2 (CTP2).
The request that was sent to the IIS server was greater than 4 GB, which is not supported. Try using a smaller value for the 'UploadGenerationsPerBatch' parameter.
When you are using Web synchronization, the size of the uploaded message must not be larger than 4 GB.
Decrease the value for the UploadGenerationsPerBatch parameter.