Wordpress Multisite “Error establishing a database connection” in localhost

Question

When attempting to convert WordPress to a Multisite setup, I get the error:

Error establishing a database connection

I\'m using

Answer 1

I had a strange encounter very recently. After setting up a dev server which runs under a different domain and moving a multisite setup to it I got the same error “Error establishing a database connection”. I had checked that all the wp_options tables have the correct domains in the respective settings and that my database connection had the right credentials and would work under normal circumferences.

I found a way to get a better error reporting. I added an output of the database object in the function dead_db() in functions.php which then showed me that it couldn’t find any blogs for my site in the table wp_blogs. I simply forgot to update the domains for the test server in this table.

function dead_db() {
  global $wpdb;

  echo "
";
  print_r($wpdb);
  echo "
";

  wp_load_translations_early();

Hope that helps someone :)