There are many possibilities that causes this error. There might be your theme is not comaptible to wordpress 4.6.1
Please make on debug mode by writing change below lines in wp_config.php from
define('WP_DEBUG', false);
to
define('WP_DEBUG', true);
and add below line to make debug log on
define('WP_DEBUG_LOG', true);
And then run your front end and go to wp-content folder, here you will find debug.log file, open this file and check error. If error is related to max execution time related then please increase max execution time of your hosting.
From this error log, try to solve error.
You can directly chat or contact also your hosting provider.