Why can’t I login to my WordPress dashboard?

Solution:

Usually white pages in WordPress are attributed to fatal PHP errors. I recommend enabling the WP_DEBUG settings inside of WordPress’s wp-config.php in the root directory.

define('WP_DEBUG', true);

This will cause PHP errors, warnings and notices to display across the entire site. If this is a live site and displaying errors is not an option use the following settings to log the errors but not display them.

// Enable WP_DEBUG mode
define('WP_DEBUG', true);

// Enable Debug logging to the /wp-content/debug.log file
define('WP_DEBUG_LOG', true);

// Disable display of errors and warnings 
define('WP_DEBUG_DISPLAY', false);
@ini_set('display_errors',0);