An exception occurred when trying to establish endpoint for context: Could not load file or assembly

Problem: When I Open Site in SharePoint I’m getting this error.

An exception occurred when trying to establish endpoint for context: Could not load file or assembly 'Microsoft.IdentityModel.Extensions, Version=2.0.0.0, Culture=neutral, PublicKeyToken=69c3241e6f0468ca' or one of its dependencies. Provider type not defined. (Exception from HRESULT: 0x80090017).

Solution

Go To Administrative Tools -> Local Security Policy->User Right Assignement ->

Impersonate a Client after authentication-> Select and click  Add application pool Account

Logon batch job->Add application pool account and

Reset IIS-> Open Cmd prompt as Admin type  iisreset