For easier integration with third-party identity providers, you can
turn off case-sensitivity of Federation IDs for your entire Salesforce org. Previously, it was
possible to create two unique users with similar Federation IDs because Salesforce recognized
case-sensitivity; for example, ssmith and SSmith. Because some external identity providers don’t
consistently recognize case-sensitivity, this created authentication issues.
Where: This change applies to Lightning Experience and Salesforce Classic in Enterprise,
Performance, Unlimited, and Developer editions.
How: To use Federation IDs without case-sensitivity, go to Setup, then Single Sign-On
Settings. Under Federated Single Sign-On, select Make Federation ID