Use the Readiness Check to Guide Your Lightning Experience Transition
Where: This change applies to Lightning Experience and Salesforce Classic in Professional, Enterprise, Performance, Unlimited, and Developer editions.
Why: Your customized Readiness Report helps you evaluate which profiles and features are most ready for Lightning Experience, and prioritize your work as you transition your org.
How: The Readiness Check is available to admins in sandbox and production environments. To run the Readiness Check in your sandbox environment, visit https://sb-lightning-readiness-check.salesforce.com/home. To run it in your production environment, go to https://lightning-readiness-check.salesforce.com/home. You can also still run the Readiness Check from the Lightning Expereince Transition Assistant.
To view the Readiness Check report, click the link in the email you receive when the check is completed. Or, log in to Salesforce and check your Salesforce files.