Migrating a WordPress multisite install involving domain name changes is a bit different than migrating a single WordPress install. Below is a list of places you’ll need to update the site urls to avoid obscure errors like “Error establishing a database connection” that aren’t actually helpful when diagnosing.
- wp-config.php – ‘DOMAIN_CURRENT_SITE‘
- wp_blogs table – domain column
- wp_site table – domain column
- wp_options and wp_*_options tables – ‘siteurl‘ and ‘home‘ option values
That should get you to where the site will load and you can log in. You’ll still need to search and replace urls in the post content using a tool like Search Replace DB 2 or the Search Regex plugin.