WordPress: Error establishing a database connection

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If you see the infamous "Error establishing a database connection", enable WordPress Debug Logging by following the steps outlined here: https://blogs.msdn.com/b/azureossds/archive/2015/10/09/logging-php-errors-in-wordpress.aspx

 

 

Debug.log will be saved within wp-content folder.

Possible error messages in debug.log:

[25-Jul-2016 15:34:44 UTC] PHP Warning: mysqli_real_connect(): (HY000/1045): Access denied for user 'be96d626d450b1'@'23.102.165.199' (using password: YES) in D:\home\site\wwwroot\wp-includes\wp-db.php on line 1490[25-Jul-2016 15:34:44 UTC] PHP Warning: mysql_connect(): Access denied for user 'be96d626d450b1'@'23.102.165.199' (using password: YES) in D:\home\site\wwwroot\wp-includes\wp-db.php on line 1520

 

[25-Jul-2016 15:45:38 UTC] PHP Warning: mysqli_real_connect(): (HY000/2002): php_network_getaddresses: getaddrinfo failed: No such host is known. in D:\home\site\wwwroot\wp-includes\wp-db.php on line 1490 [25-Jul-2016 15:45:38 UTC] PHP Warning: mysql_connect(): php_network_getaddresses: getaddrinfo failed: No such host is known. in D:\home\site\wwwroot\wp-includes\wp-db.php on line 1520

 

After enabling the logs, if you see the messages above, verify the database credentials within wp-config.php, highlighted below:

 

 

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[25-Jul-2016 00:03:13 UTC] PHP Warning:  mysqli_real_connect(): (HY000/1226): User 'abcdefghijk79' has exceeded the 'max_user_connections' resource (current value: 4) in D:\home\site\wwwroot\wp-includes\wp-db.php on line 1454

If this error is apparent in your debug.log or php_errors.log, then your application is exceeding the number of connections.

If you’re hosting on ClearDB, please verify the number of connections available in your service plan.

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Figure 1. Screen showing ClearDB Service Plans with max number of connections, outlined in red.

If you need assistance with upgrading your ClearDB database, contact ClearDB by emailing support@cleardb.com.

For optimizing WordPress, please see this article:  https://azure.microsoft.com/en-us/blog/10-ways-to-speed-up-your-wordpress-site-on-azure-websites/