Setting the site to dev mode revealed the sql error
Looks like its happening inside the recalculate_numbersold() function around line 114 of Product.php
[User Error] Couldn't run query: SELECT "SiteTree"."ClassName", "SiteTree"."Created", "SiteTree"."LastEdited", "SiteTree"."URLSegment", "SiteTree"."Title", "SiteTree"."MenuTitle", "SiteTree"."Content", "SiteTree"."MetaTitle", "SiteTree"."MetaDescription", "SiteTree"."MetaKeywords", "SiteTree"."ExtraMeta", "SiteTree"."ShowInMenus", "SiteTree"."ShowInSearch", "SiteTree"."HomepageForDomain", "SiteTree"."ProvideComments", "SiteTree"."Sort", "SiteTree"."HasBrokenFile", "SiteTree"."HasBrokenLink", "SiteTree"."Status", "SiteTree"."ReportClass", "SiteTree"."CanViewType", "SiteTree"."CanEditType", "SiteTree"."ToDo", "SiteTree"."Version", "SiteTree"."Priority", "SiteTree"."ParentID", "Page"."SubMenu", "Page"."PlaceInFooter", "Product"."Price", "Product"."Weight", "Product"."Model", "Product"."FeaturedProduct", "Product"."AllowPurchase", "Product"."InternalItemID", "Product"."NumberSold", "Product"."ImageID", "SiteTree"."ID", CASE WHEN "SiteTree"."ClassName" IS NOT NULL THEN "SiteTree"."ClassName" ELSE 'SiteTree' END AS "RecordClassName", SUM(OrderItem.Quantity) AS NewNumberSold FROM "SiteTree" LEFT JOIN "Page" ON "Page"."ID" = "SiteTree"."ID" LEFT JOIN "Product" ON "Product"."ID" = "SiteTree"."ID" LEFT JOIN "Product_OrderItem" ON Product.ID = Product_OrderItem.ProductID LEFT JOIN "OrderItem" ON Product_OrderItem.ID = OrderItem.ID WHERE ("SiteTree"."ClassName" IN ('Product')) AND (`Product`.`AllowPurchase` IS TRUE) GROUP BY Product.ID ORDER BY NewNumberSold DESC You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'TRUE) GROUP BY Product.ID ORDER BY NewNumberSold DESC' at line 1