Administrator unable to edit page layout in Lightning Experience

As a system Administrator, you may receive the following error message when you attempt to edit a Page Layout in Lightning Experience.
 

Error message text

'Insufficient Privileges: You do not have the level of access necessary to perform the operation you requested. Please contact the owner of the record or your administrator if access is necessary. For more information, see Insufficient Privileges Errors.'
 

Cause

This error displays because Enhanced Page Layout Editor is required but the feature has not been enabled in your organization.