Magic formula:
Most free plugin to “backup” charge your migration, when is a matter of running few lines of code on your database…
UPDATE wp_options SET option_value = replace(option_value, 'http://oldurl.com', 'https://newurl.com') WHERE option_name = 'home' OR option_name = 'siteurl';
UPDATE wp_posts SET guid = replace(guid, 'http://oldurl.com','https://newurl.com');
UPDATE wp_posts SET post_content = replace(post_content, 'http://oldurl.com', 'https://newurl.com');
UPDATE wp_postmeta SET meta_value = replace(meta_value,'http://oldurl.com','https://newurl.com');
UPDATE wp_revslider_slides SET params = replace(params, 'oldurl.com', 'newurl.com');
// last line only needed if you use revslider, a lot of themes do now...
AC.