We are using Version 7.8. The error that shows up in the log is as follows:
<message>There was an error generating the XML document.</message><exception>System.InvalidOperationException: There was an error generating the XML document. ---> System.InvalidOperationException: Value of ItemElementName mismatches the type of System.DateTime; you need to set it to DocuWare.Platform.Model.ItemChoiceType.@Date.
This happens when uploading any file over 3mb, anything less and there is no issues. Currently, I'm not changing anything about the Date index field or any index fields including DateTime. This would be an index field coming from DocuWare itself. I've had success in uploading a file with 10mb of data without sending the index fields along with it. I've tried creating new Index fields without mentioning the dates and it will still throw an error about DateTime.