_code_changes_NET3.4_vs_4.6.1.txt

Upgrading form .NET 3.5 to .NET 4.61 
we had to change the option settings for the 
following libraries in the References section 
of the Solution Explorer panel

Property:                    EmbedInteropTypes

Library                      original  changed to
ESRI.ArcGIS.Carto            TRUE      FALSE
ESRI.ArcGIS.DataSourcesFile  TRUE      FALSE
ESRI.ArcGIS.Display          TRUE      FALSE
ESRI.ArcGIS.Geodatabase      TRUE      FALSE
ESRI.ArcGIS.Geometry         TRUE      FALSE


for more see at:
https://knowledge.ni.com/KnowledgeArticleDetails?id=kA00Z000000P8CVSA0
https://community.esri.com/thread/181313
https://gis.stackexchange.com/questions/298043/setting-embed-interop-types-in-arcobjects-to-true-or-false