Flag does not exist

Make sure your view has selected a valid flag. If you imported a view you found in the documentation, for example, you may have different flag names set up than were specified in the imported view.

This is probably a bug on Flag's end as it should really check whether get_flag() returns null before attempting to access its properties.

Also make sure that the Flag classes are loaded before FBSS's by ensuring that the weight of the "facebook_status" record is heavier than that of the "flag" record in the {system} table, but I really doubt this is the problem because FBSS makes that change for you automatically when installing the module.

I'll fix this in #901116: Views validation: guard against non-existent flags. Marking this as dup.