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 WordPress 3.7.1 on Windows 7 with a WAMP server.

wp-config.php

define('WP_ALLOW_MULTISITE', true );  define('SUBDOMAIN_INSTALL', false);  define('DOMAIN_CURRENT_SITE', 'localhost'); define('PATH_CURRENT_SITE', '/wordpress_test4/'); define('SITE_ID_CURRENT_SITE', 1);  define('BLOG_ID_CURRENT_SITE', 1); 

.htaccess

RewriteEngine On  RewriteBase /wordpress_test4/  RewriteRule ^index\.php$ - [L]  # add a trailing slash to /wp-admin  RewriteRule ^([_0-9a-zA-Z-]+/)?wp-admin$ $1wp-admin/ [R=301,L]  RewriteCond %{REQUEST_FILENAME} -f [OR]  RewriteCond %{REQUEST_FILENAME} -d  RewriteRule ^ - [L]  RewriteRule ^([_0-9a-zA-Z-]+/)?(wp-(content|admin|includes).*) $2 [L]  RewriteRule ^([_0-9a-zA-Z-]+/)?(.*\.php)$ $2 [L]  RewriteRule . index.php [L] 

Answer 1

You need to add to your wp-config.php:

define('MULTISITE', true); 

I had the same problem. I skipped this line because I already had define('WP_ALLOW_MULTISITE', true); in my wp-config and it looked to me the same.

Answer 2

Had same problem, found 3 possible solutions:

1. Make sure: DB_NAME, DB_USER, DB_PASSWORD, and DB_HOST in your wp-config.php are really the ones expectected.

2. As Dima L. mentioned before, define('MULTISITE', true); is expected too.

3. But what solved it for me* is etting up multi-site for WordPress, changed the wp_blogs table's column path to an undefined location for my website. I changed it to / and the DB connection was re-established.