I installed the hestia theme from the themes listed in the dashboard. All other themes worked fine but this one causes Wordpress to crash and I am unable to login though, interestingly, I can view the hestia demo site installed on my system.
So what do I need to do to be able to log in to Wordpress or remove the hestia theme or fix the error? Here is the error on all pages other than the hestia demo:
Fatal error: Uncaught Error: Call to undefined function filter_var() in /usr/local/www/wordpress/wp-content/plugins/wpforms-lite/includes/admin/class-am-deactivation-survey.php:88
Stack trace: #0 /usr/local/www/wordpress/wp-content/plugins/wpforms-lite/includes/admin/class-am-deactivation-survey.php(53): AM_Deactivation_Survey->is_dev_url()
#1 /usr/local/www/wordpress/wp-content/plugins/wpforms-lite/src/WPForms.php(298): AM_Deactivation_Survey->__construct('WPForms', 'wpforms-lite')
#2 /usr/local/www/wordpress/wp-includes/class-wp-hook.php(286): WPForms\WPForms->objects('')
#3 /usr/local/www/wordpress/wp-includes/class-wp-hook.php(310): WP_Hook->apply_filters(NULL, Array)
#4 /usr/local/www/wordpress/wp-includes/plugin.php(465): WP_Hook->do_action(Array)
#5 /usr/local/www/wordpress/wp-settings.php(394): do_action('plugins_loaded') #6 /usr/local/www/wordpress/wp-config.php(93): require_once('/usr/local/www/...')
#7 /usr/local/www/wordpress/wp-load.php(37): require_once('/usr/local/www/...')
#8 /usr/local/www/wordpress/wp-ad in /usr/local/www/wordpress/wp-content/plugins/wpforms-lite/includes/admin/class-am-deactivation-survey.php on line 88
The site is experiencing technical difficulties. Please check your site admin email inbox for instructions.
EDIT: Elsewhere I read that I can go to wp-content/themes and remove the theme folder but that did not fix anything.