Error with automatically updating Wordpress in Plesk

Question

Plek tries to update my Wordpress but gives this error.

Does anyone know how I can reset the cache, or have an other solution?

1. Website "Domain" (https://www.domain.nl): Failed to reset cache for the instance #1: PHP Warning: Creating default object from empty value in /var/www/vhosts/server.nl/domain-v2/wp-content/plugins/dfd-extensions/redux_framework/ReduxCore/inc/class.redux_filesystem.php on line 29
Warning: Creating default object from empty value in /var/www/vhosts/server.nl/domain-v2/wp-content/plugins/dfd-extensions/redux_framework/ReduxCore/inc/class.redux_filesystem.php on line 29
PHP Warning: "continue" targeting switch is equivalent to "break". Did you mean to use "continue 2"? in /var/www/vhosts/server.nl/domain-v2/wp-content/plugins/revslider/includes/operations.class.php on line 2854
Warning: "continue" targeting switch is equivalent to "break". Did you mean to use "continue 2"? in /var/www/vhosts/server.nl/domain-v2/wp-content/plugins/revslider/includes/operations.class.php on line 2854
PHP Warning: "continue" targeting switch is equivalent to "break". Did you mean to use "continue 2"? in /var/www/vhosts/server.nl/domain-v2/wp-content/plugins/revslider/includes/operations.class.php on line 2858
Warning: "continue" targeting switch is equivalent to "break". Did you mean to use "continue 2"? in /var/www/vhosts/server.nl/domain-v2/wp-content/plugins/revslider/includes/operations.class.php on line 2858
PHP Warning: "continue" targeting switch is equivalent to "break". Did you mean to use "continue 2"? in /var/www/vhosts/server.nl/domain-v2/wp-content/plugins/revslider/includes/output.class.php on line 3708
Warning: "continue" targeting switch is equivalent to "break". Did you mean to use "continue 2"? in /var/www/vhosts/server.nl/domain-v2/wp-content/plugins/revslider/includes/output.class.php on line 3708
PHP Fatal error: Uncaught Error: Class 'Dfd_Theme_Helpers' not found in /var/www/vhosts/server.nl/domain-v2/wp-content/plugins/dfd-extensions/vc_custom/dfd_vc_addons.php:821
Stack trace:
#0 /var/www/vhosts/server.nl/domain-v2/wp-content/plugins/dfd-extensions/dfd_extensions.php(142): require_once()
#1 /var/www/vhosts/server.nl/domain-v2/wp-includes/class-wp-hook.php(288): Dfd_Theme_extensions->addVcCustomElements()
#2 /var/www/vhosts/server.nl/domain-v2/wp-includes/class-wp-hook.php(312): WP_Hook->apply_filters()
#3 /var/www/vhosts/server.nl/domain-v2/wp-includes/plugin.php(478): WP_Hook->do_action()
#4 /var/www/vhosts/server.nl/domain-v2/wp-settings.php(507): do_action()
#5 /opt/psa/admin/plib/modules/wp-toolkit/vendor/wp-cli/vendor/wp-cli/wp-cli/php/WP_CLI/Runner.php(1291): require('/var/www/vhosts...')
#6 /opt/psa/admin/plib/modules/wp-toolkit/vendor/wp-cli/vendor/wp-cli/wp-cli/php/WP_CLI/Runner.php(1212): WP_CLI\Runner->l in /var/www/vhosts/server.nl/domain-v2/wp-content/plugins/dfd-extensions/vc_custom/dfd_vc_addons.php on line 821
Fatal error: Uncaught Error: Class 'Dfd_Theme_Helpers' not found in /var/www/vhosts/server.nl/domain-v2/wp-content/plugins/dfd-extensions/vc_custom/dfd_vc_addons.php:821
Stack trace:
#0 /var/www/vhosts/server.nl/domain-v2/wp-content/plugins/dfd-extensions/dfd_extensions.php(142): require_once()
#1 /var/www/vhosts/server.nl/domain-v2/wp-includes/class-wp-hook.php(288): Dfd_Theme_extensions->addVcCustomElements()
#2 /var/www/vhosts/server.nl/domain-v2/wp-includes/class-wp-hook.php(312): WP_Hook->apply_filters()
#3 /var/www/vhosts/server.nl/domain-v2/wp-includes/plugin.php(478): WP_Hook->do_action()
#4 /var/www/vhosts/server.nl/domain-v2/wp-settings.php(507): do_action()
#5 /opt/psa/admin/plib/modules/wp-toolkit/vendor/wp-cli/vendor/wp-cli/wp-cli/php/WP_CLI/Runner.php(1291): require('/var/www/vhosts...')
#6 /opt/psa/admin/plib/modules/wp-toolkit/vendor/wp-cli/vendor/wp-cli/wp-cli/php/WP_CLI/Runner.php(1212): WP_CLI\Runner->l in /var/www/vhosts/server.nl/domain-v2/wp-content/plugins/dfd-extensions/vc_custom/dfd_vc_addons.php on line 821
Error: Er heeft zich een kritische fout voorgedaan op je website.Lees meer over probleemoplossing in WordPress. Er heeft zich een kritische fout voorgedaan op je website.


2. Website "Domain" (https://staging.domain.nl): Failed to reset cache for the instance #5: PHP Fatal error: Uncaught Error: Class 'Dfd_Theme_Helpers' not found in /var/www/vhosts/server.nl/staging.domain.nl/wp-content/plugins/dfd-extensions/vc_custom/dfd_vc_addons.php:830
Stack trace:
#0 /var/www/vhosts/server.nl/staging.domain.nl/wp-content/plugins/dfd-extensions/dfd_extensions.php(144): require_once()
#1 /var/www/vhosts/server.nl/staging.domain.nl/wp-includes/class-wp-hook.php(307): Dfd_Theme_extensions->addVcCustomElements()
#2 /var/www/vhosts/server.nl/staging.domain.nl/wp-includes/class-wp-hook.php(331): WP_Hook->apply_filters()
#3 /var/www/vhosts/server.nl/staging.domain.nl/wp-includes/plugin.php(474): WP_Hook->do_action()
#4 /var/www/vhosts/server.nl/staging.domain.nl/wp-settings.php(565): do_action()
#5 /opt/psa/admin/plib/modules/wp-toolkit/vendor/wp-cli/vendor/wp-cli/wp-cli/php/WP_CLI/Runner.php(1291): require('/var/www/vhosts...')
#6 /opt/psa/admin/plib/modules/wp-toolkit/vendor/wp-cli/vendor/wp-cli/wp-cli/php/WP_CLI/Runn in /var/www/vhosts/server.nl/staging.domain.nl/wp-content/plugins/dfd-extensions/vc_custom/dfd_vc_addons.php on line 830
Fatal error: Uncaught Error: Class 'Dfd_Theme_Helpers' not found in /var/www/vhosts/server.nl/staging.domain.nl/wp-content/plugins/dfd-extensions/vc_custom/dfd_vc_addons.php:830
Stack trace:
#0 /var/www/vhosts/server.nl/staging.domain.nl/wp-content/plugins/dfd-extensions/dfd_extensions.php(144): require_once()
#1 /var/www/vhosts/server.nl/staging.domain.nl/wp-includes/class-wp-hook.php(307): Dfd_Theme_extensions->addVcCustomElements()
#2 /var/www/vhosts/server.nl/staging.domain.nl/wp-includes/class-wp-hook.php(331): WP_Hook->apply_filters()
#3 /var/www/vhosts/server.nl/staging.domain.nl/wp-includes/plugin.php(474): WP_Hook->do_action()
#4 /var/www/vhosts/server.nl/staging.domain.nl/wp-settings.php(565): do_action()
#5 /opt/psa/admin/plib/modules/wp-toolkit/vendor/wp-cli/vendor/wp-cli/wp-cli/php/WP_CLI/Runner.php(1291): require('/var/www/vhosts...')
#6 /opt/psa/admin/plib/modules/wp-toolkit/vendor/wp-cli/vendor/wp-cli/wp-cli/php/WP_CLI/Runn in /var/www/vhosts/server.nl/staging.domain.nl/wp-content/plugins/dfd-extensions/vc_custom/dfd_vc_addons.php on line 830
Error: Er heeft zich een kritieke fout voorgedaan op deze site.Meer informatie over probleemoplossing in WordPress. Er heeft zich een kritieke fout voorgedaan op deze site.

I have the latest version of Plek Onyx with the Wordpress toolkit I also tried to update it manually in Plesk, but it gives the same error