The error presented looks like this with the following error, "An unknown error has occurred.": 

To resolve follow these steps:

1. After logging into LibGuides, go into LibCal.
   
   
   
   
   
2. Under Admin, go to Spaces and Equipment
   
   
   
   
3. Under Spaces and Equipment, click on the Edit Location icon on the same line as your location.
   
   
   
   
   
4. Under the General tab, scroll down until you see Activate LibAuth (LDAP/Shibboleth/CAS etc.). Choose a different authentication option and then test to see if authentication works.