How to fix SSO error when trying to access Support Cases?

If you experience Single Sign-On error when accessing Support Cases and / or Knowledge Base, make sure you delete cache for All time and type in support.paloaltonetworks.com / https://supportcases.paloaltonetworks.com.  Do not use a bookmarked page. 
(Please note that if the user is assigned a role that does not include access to 'Case Management' as outlined in the Support Portal User Role Matrix in the CSP, they will not be able to access Support Cases or the Knowledge Base and will encounter a Single Sign-On error.
To obtain an appropriate user role, please contact your superuser and request that they assign the appropriate role.)

If deleting cache does not resolve the issue, you will need to visit the Customer Support Portal home page for further assistance.
If you have more than one Customer Support Portal user login, indicate in the description field which CSP account is affected.