Getting Unknown Error on this page?.
No helpful clue in Sharepoint log or Event Viewer?
This can happen if database record in the list of published InfoPath forms had a null where it shouldn’t be.
Thanks to this blog, there is small code snippet given here which will delete the culprit entry.
make sure that you run this script under the debugger and only execute
the delete operation for the offending form, otherwise it will delete
all the published forms in your farm.