You may notice that after downgrading, you receive and error like:
Unknown column 'view_php' in 'field list' query:..sites/all/modules/views/includes/view.inc on line 1722.
If so, backup your database and then run this mySQL query:
ALTER TABLE views_view ADD is_cacheable tinyint;
ALTER TABLE views_view ADD view_php blob;
Worked for me!
Apart from that, be sure that you've clear all of the Header, Footer, and Empty Text fields from all of your views.