On two different sites today got 2 different errors. Am not using Gravity Forms extensions on either of these sites. Just simple contact forms. Both are on StudioPress Genesis themes. Site 1 is a dev site. Site 2 is a mature site on a recent Genesis theme.
Message Site 1: Dev site.
WordPress database error: [Duplicate column name 'confirmations']
ALTER TABLE wp_rg_form_meta ADD COLUMN confirmations longtext
Message Site 2 ItsDifferent4Girls.com:
WordPress database error: [Duplicate key name 'lead_field_number']
ALTER TABLE wp_rg_lead_detail ADD KEY lead_field_number (lead_id,field_number)