If you receive an error with your WordPress network, chances are that it is due to a failure that happens when WordPress cannot find one or more of the global tables for the network in the database. There are three major steps to walk through in the debugging process. This will help you to cover all your bases before seeking further help.

Step 1: Check with your host to make sure that your account fulfills the technical requirements for a Multisite network.

If your account is not equipped to run multisite, then your host may have disabled the functionality from running, which will result in errors. Check with your host to see if you need to upgrade your account.

Step 2: Inspect your wp-config.php file.

Check wp-config.php for the following:

• correct database details
• SUBDOMAIN_INSTALL constant
• MULTISITE constant
• $base variable
• table prefix

If you have any code after this line, then it needs to be moved up above the “stop editing line”:

require_once(ABSPATH . 'wp-settings.php');

Step 3: Check your database.

Check to make sure that all of the extra network tables have been created:

• wp_blogs
• wp_blog_versions
• wp_registration_log
• wp_signups
• wp_site
• wp_sitemeta

For a complete overview and description of all Multisite database tables, check out the breakdown in the WordPress codex.

Another unusual reason that site creation might stop working on your network is that the location of the database server may have changed. In that case you’ll need to update your wp-config.php file. After covering all these bases, then you’re sure to hit the forums with the full knowledge that you’ve done a thorough check through all the usual suspects.