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.

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.

• fatal-error

• This can only happen if your PHP version is older than 5.2.0. Please make sure your PHP is up to date (7.2 or 7.3). – fuxia ♦ Commented Aug 18, 2019 at 12:23
• @fuxia I am at 7.2.21 – Rob Commented Aug 18, 2019 at 12:26

4 Answers 4

Removing all plugins is a drastic method to fix a simple problem. (Which is why I gave that answer a downvote.)

The error messages indicate a problem with a specific plugin. You can rename or delete the folder for that plugin. Renaming the plugin's folder will disable it. Removing the plugin's folder will disable it without possibility to recover.

So, as the other person mentioned in their answer, the problem doesn't appear to be in the theme, but in the plugin causing the error message.

If the plugin's features are important to you, you could try reinstalling the plugin's files via an FTP from the latest version of the plugin that you download. Or you could rename the plugin's folder and reinstall it.

But removing/deleting all plugins to fix a problem is like taking a giant Thor hammer to put a nail in the wall for a picture. Rename the entire wp-content/plugins folder to something else to temporarily disable all plugins, then copy individual plugins folder into a newly created wp-content/plugins folder to re-enable that plugin to check if that plugin is causing the error.

But, a careful reading of the error message will usually point in the direction to go. Use the 'scalpel of renaming things, rather than the "Thor's Hammer" of a massive deletion of all plugins.

To remove a theme its usually enough to login via FTP and delete or remove the theme folder from wp-content/themes. Wordpress will then automatically look for a standard theme like TwentyNineteen (make sure its installed and in the above mentioned theme folder).

But in your case the error says it's a plugin called "wp forms lite". Remove that from wp-content/plugins and everything should work again. If both theme and plugin wrote to your database you should clean it - but backup it before.

The problem is not with your theme. The error has been caused by one of your plugins with name wpforms-lite.

Just FTP to your website, go to plugins folder and change the name of wpforms-lite to something else like wpforms-lite-2

This will disable the plugin in WordPress.

Now try reloading your website. If it works fine, the problem was in the plugin.

you can disable or rename plugin and install latest new plugin via FTP.

And also you should check PHP version, might be that plugin/theme requires newer version of PHP.

hope this info will be helpful for you.