Unable to load DLL 'sni.dll': Access is denied - when connection to SQL server
If your helpdesk application v.10 and later does not work and you're getting "Unable to load DLL 'sni.dll': Access is denied" error in the server "event viewer" this means the app has trouble connecting to the database server.
This is a rare error, but it does happen at some of our clients.
According to Microsoft https://docs.microsoft.com/en-us/sql/connect/ado-net/sqlclient-troubleshooting-guide?view=sql-server-ver15#issues-in-net-core-applications the workaround is to grant "execute" permissions to the "sni.dll" file found in the application folder for the ApplicationPool user account.
sni.dll is a C++ library that is required for .NET apps that connect to SQL server on Windows (on Linux it's not needed).