Forum Post: RE: I am trying to write a plugin which has to search through files in sharepoint and return path. For I need to use assembly -- "'Microsoft.SharePoint.Client.Search, Version=16.1.0.0," But error says,above assembly could not be loaded.

if it is an online instance (meaning you can only register the assembly in sandbox) the alternatives are two: 1) try to merge the assemblies with ILMERGE (there are guides to do this for dynamics plugins as you need to keep consistent the signing) 2) create a public reachable webservice to perform the action and inside your plugin you call the webservice and return the results