WordPress Login page redirected to sub-directory, gets http 500 error?

Solution: 

Check the database table wp_options and the site URL and base URL should be http://example.com Alternatively, you can define site URL and base URL in wp-config.php too

define( 'WP_HOME', 'http://example.com' );
define( 'WP_SITEURL', 'http://example.com' );