Wordpress Multisite “Error establishing a database

问题:

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]

回答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.

回答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. (what solved it for me) Setting 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.

回答3:

I struggled a long time because of this issue. And finally found a solution.

You should not add all those settings at once in the wp-config.php file. Follow the exact steps described here: http://codex.wordpress.org/Create_A_Network

Only add the following code as the first step:

/* Multisite */
define( 'WP_ALLOW_MULTISITE', true );

And then refresh your page. After that, in your administration panel go to Tools -> Network Setup and choose your sub-site settings.

For the rest, just use the instructions from the link above.

Good luck!

回答4:

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 "<pre>";
  print_r($wpdb);
  echo "</pre>";

  wp_load_translations_early();

Hope that helps someone :)

回答5:

My DOMAIN_CURRENT_SITE in wp-config.php was define('DOMAIN_CURRENT_SITE', 'www.example.com');

Removing "http://" in wp_blogs -> domain fixed my issue.

回答6:

Besides to all said above, if working with multisite environment please check also the following: in the respective subdirectories (/home/subsitename) there exist separate wp-config.php and .htaccess files for each of (sub)sites, so the above mentioned parameters have to be adjusted in all of these files. For example, my main site was working correctly since these files in my /home directory were OK, but when tried to access my sub-sites, I've been receiving database connection error message until I adjusted these files too.

回答7:

I added $base = '/'; into config, which solved issue.

define('MULTISITE', true);
define('SUBDOMAIN_INSTALL', true);
define('DOMAIN_CURRENT_SITE', 'mydomain.com');
$base = '/';
define('PATH_CURRENT_SITE', '/');
define('SITE_ID_CURRENT_SITE', 1);
define('BLOG_ID_CURRENT_SITE', 1);

回答8:

If you're running WHM/cPanel and you've already checked that you've added the MULTISITE/WP_ALLOW_MULTISITE constant, you're probably running into virtual host issues.

If you're getting the database error, chances are, your name servers or A record is correct. Otherwise your domain wouldn't be pointing to your server with a database connection. But, you've probably forgotten, or missed, the domain name from the cPanel aliases.

Just head to cPanel, search for 'Aliases' and type in the domain name you're missing under 'Create a New Alias'.

You can also get to cPanel by logging into WHM, searching for 'List Accounts', searching for the account you want and clicking on the CP icon.

回答9:

Here's How I fixed it

config settings

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

then in the database table (found using phpmyadmin) wp_blogs set the values for your root blog (which should be lie/number 1) to

domain localhost
root /myblog/

And finally - reset the sitrurl and homepage in options table (again found using phpmyadmin) to

 http://localhost/myblog/

回答10:

Inspired by Sabin's answer, I checked wp_blogs and found that the domain value was still pointing to the wrong domain (I was moving a multi-site to a dev server). Running UPDATE wp_blogs SET domain='example.com'; fixed my issue (note that I'm using subfolder multisite, not subdomain - don't blindly run that SQL!)

回答11:

I had the problem after moving the multisite from a sub directory to the root directory. Wat solved it for me was partly what has been mentioned by Sabin Chirila : 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. Change the 'wp_blogs' table's column 'path' to "/" and the DB connection was re-established.

but I had to change some more things.

4. In order to be able to view the frontend I also had to change the 'wp_site’ table's column 'path' to "/"
5. and then (in theme twentyseventeen-child) I had to reconfigure some configuration settings in the backend as they weren't taken into account. But that was simple as the data was still there.