Can I deploy my SOE or SOI built with an older version of the ArcObjects SDK to a newer version of ArcGIS Server?
Currently, deploying an older version of an SOE or SOI created with the ArcObjects SDK to a newer version of ArcGIS Server is not a supported or certified workflow. Even though an SOE or SOI in some cases may still function well when it’s deployed to a newer version of ArcGIS Server, there is no guarantee that this would work for all the SOEs and SOIs. For example, when third-party components or libraries are used. The best practice is to recompile the SOE or SOI using the same version of ArcObjects SDK as the version of ArcGIS Server where the extension will be deployed.