Integrated login error in Service Portal

Problem:

A runtime error occurs in Service Portal while using integrated login and no application event log error entries on the web server are seen. You get the error message also while trying the integrated login for portal directly on the web server. This happens for a particular role (e.g. PortalEndUser) only and users from other role are logging fine with integrated login.

Cause:

Read and Update privileges for User Network Login are missing for that particular role

Solution:

Set read and update permissions on the "User Network Login" for the particular role. You will find this privilege in Console > Administration > User Management > Choose your role in "Roles" > Modules > System > Non-Process Related Objects >  User Network Login

You will need an IIS reset after this is set. The role "PortalEndUser" does not have this privilege by default.