This article was created in response to a support issue logged with K2. The content may include typographical errors and may be revised at any time without notice This article is not considered official documentation for K2 software and is provided “as is” with no warranties.
The issue stems from a scenario in which two document set content types mapped to one document library share the same site column. Under these circumstances when getDocumentSets() is fired the exception 'Sequence contains more than one matching element' appears.
'Sequence contains more than one matching element' appears when getDocumentSets() is fired.
This issue was resolved in FixPack 25.