Symptoms

When submitting a InfoPath for on a claims enabled site, we saw an error. Looking at the host server logs and the SP ULS logs, we saw the following errors during the same time period. Error: ProcessPacket Error, Claims token XML is empty.
 

Diagnoses

In some cases our InfoPath runtime service fails to detect the site as a claims site. When this happens, we assume that it is a Windows auth site and then authentication fails.
 

Resolution

If you run into this issue, please log a ticket and request the cold-fix. After applying a cold-fix that LABS provided, all was well. (This fix will be included in a future build of K2 blackpearl.)