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Debugging a WordPress website

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Dave Panter
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WordPress includes several settings that you can use to help debug the main application, themes, custom code, and more.
Note: Before making any changes to your WordPress configuration file, make a backup of the file in place.

Enabling debugging mode

Generally, these settings are intended for use by developers and should not be used on live sites. However, you can also use them in specific scenarios to help troubleshoot issues you may be experiencing with third-party code, such as plugins or themes.

To enable debugging mode in WordPress, follow these steps.

  1. Log in to cPanel.
  2. Using the cPanel File Manager or your preferred text editor, open the wp-config.php.
  3. To enable debugging mode, add the following line to the wp-config.php file.
    Note: When this setting is enabled, WordPress displays all PHP errors, notices, and warnings.
    define('WP_DEBUG', true);
  4. Save your changes and exit the text editor. Debugging mode is now active.
    Note: Disable debugging mode by modifying the line in the wp-config.php file as follows
    define('WP_DEBUG', false);

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Additional debug options

There are several additional settings you can use to control the debugging information that WordPress provides.

WP_DEBUG_LOG


When WP_DEBUG_LOG and WP_DEBUG are enabled, WordPress saves all error information to the debug.log file in the wp-content directory. By default, this setting is disabled.
To enable this setting, add the following line to the wp-config.php file.

define('WP_DEBUG_LOG', true);

WP_DEBUG_DISPLAY


When WP_DEBUG_DISPLAY and WP_DEBUG are enabled, WordPress displays errors and warning messages on web pages. By default, this setting is enabled. When this setting is disabled, debugging messages are hidden from view.
To disable this setting, add the following line to the wp-config.php file.

define('WP_DEBUG_DISPLAY', false);

SCRIPT_DEBUG


When SCRIPT_DEBUG is enabled, WordPress uses development versions of core CSS and JavaScript files instead of the compressed versions typically used. This setting is disabled by default. Use this setting to test modifications to built-in .js or .css files.
To enable this setting, add the following line to the wp-config.php file.

define('SCRIPT_DEBUG', true);

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Logging database queries

If you are experiencing database issues with WordPress, you can enable query logging. When query logging is enabled, the following items are saved in the global $wpdb->queries array.

  • The actual database query
  • How long the query takes to run
  • The function which called the query

To enable database query logging, add the following line to the wp-config.php file.
Note: Enabling this setting affects your site's performance. You should only enable this setting for as long as it is necessary to debug a problem.  Once finished, make sure to disable it.

define('SAVEQUERIES', true);

The following PHP code snippet demonstrates how to dump the entire contents of the $wpdb->queries array to a page.

<?php
    global $wpdb;
    print_r( $wpdb->queries );
?>

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