Upload document into document library using smartfrom give "Content type not found" error

I have created smartfiorm for document library using documnet library smartobject. I have some extra metadata field in document library other than default fields. Using document library smartobject I created one view, same view using in smartform.

When I am trying to upload the document using smartform i am getting "Content type not found" error. Even after getting the error document is getting updated in library but metadata is not updating.

If I use default SharePoint form then its working fine. Please let me know what may be the issue.

Attached is the error screenshot.

Also, I found one article in K2 knowledge center which says, we cant use smart forms for document library for upload documents.

https://help.k2.com/kb001799 

Please let me know any solution.

Thanks,

Prafull