Having this issue since couple days. Search was working fine before that. Getting below error.
I already tried couple things from some posts.
Added the following to the web.config file.
SafeControl Assembly="Microsoft.Office.Server.Search, Version=15.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c" Namespace="Microsoft.Office.Server.Search.Internal.UI" TypeName="*" Safe="True"
SafeControl Assembly="Microsoft.Office.Server.Search, Version=16.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c" Namespace="Microsoft.Office.Server.Search.Internal.UI.SearchAdministration" TypeName="*" Safe="True"
PageParserPath VirtualPath="/searchadministration.aspx" CompilationMode="Always" AllowServerSideScript="true"
Still no luck accessing the search service to perform a crawl since list and site search not getting any results back. any help is appreciated.