Php error

Hello, unfortunately after updating PHP to version 8.0 I started getting the following errors. I rolled back to 7.4 but the problem persists.

2023-10-05T12:00:36+00:00 CRITICAL Uncaught TypeError: strstr(): Argument #1 ($haystack) must be of type string, WP_Error given in /home/armadabg/web/armadabg.eu/public_html/wp-includes/functions.php:1144
Stack trace:
#0 /home/armadabg/web/armadabg.eu/public_html/wp-includes/functions.php(1144): strstr()
#1 /home/armadabg/web/armadabg.eu/public_html/wp-includes/functions.php(1217): add_query_arg()
#2 /home/armadabg/web/armadabg.eu/public_html/wp-content/plugins/woocommerce/includes/widgets/class-wc-widget-layered-nav.php(423): remove_query_arg()
#3 /home/armadabg/web/armadabg.eu/public_html/wp-content/plugins/woocommerce/includes/widgets/class-wc-widget-layered-nav.php(187): WC_Widget_Layered_Nav->layered_nav_list()
#4 /home/armadabg/web/armadabg.eu/public_html/wp-includes/class-wp-widget.php(394): WC_Widget_Layered_Nav->widget()
#5 /home/armadabg/web/armadabg.eu/public_html/wp-includes/widgets.php(837): WP_Widget->display_callback()
#6 /home/armadabg/web/armadabg.eu/public_html/wp-content/themes/flatsome/woocommerce/layouts/category.php(17): dynamic_sidebar()
#7 /home/armadabg/web/armadabg.eu/public_html/wp-includes/template.php(787): require('...')
#8 /home/armadabg/web/armadabg.eu/public_html/wp-content/plugins/woocommerce/includes/wc-core-functions.php(284): load_template()
#9 /home/armadabg/web/armadabg.eu/public_html/wp-content/themes/flatsome/woocommerce/archive-product.php(27): wc_get_template_part()
#10 /home/armadabg/web/armadabg.eu/public_html/wp-content/plugins/woocommerce/includes/wc-core-functions.php(345): include('...')
#11 /home/armadabg/web/armadabg.eu/public_html/wp-content/plugins/woocommerce/templates/taxonomy-product-cat.php(22): wc_get_template()
#12 /home/armadabg/web/armadabg.eu/public_html/wp-includes/template-loader.php(106): include('...')
#13 /home/armadabg/web/armadabg.eu/public_html/wp-blog-header.php(19): require_once('...')
#14 /home/armadabg/web/armadabg.eu/public_html/index.php(17): require('...')
#15 {main}
  thrown в /home/armadabg/web/armadabg.eu/public_html/wp-includes/functions.php на ред 1144

2023-10-05T12:00:46+00:00 CRITICAL Uncaught TypeError: strstr(): Argument #1 ($haystack) must be of type string, WP_Error given in /home/armadabg/web/armadabg.eu/public_html/wp-includes/functions.php:1144
Stack trace:
#0 /home/armadabg/web/armadabg.eu/public_html/wp-includes/functions.php(1144): strstr()
#1 /home/armadabg/web/armadabg.eu/public_html/wp-includes/functions.php(1217): add_query_arg()
#2 /home/armadabg/web/armadabg.eu/public_html/wp-content/plugins/woocommerce/includes/widgets/class-wc-widget-layered-nav.php(423): remove_query_arg()
#3 /home/armadabg/web/armadabg.eu/public_html/wp-content/plugins/woocommerce/includes/widgets/class-wc-widget-layered-nav.php(187): WC_Widget_Layered_Nav->layered_nav_list()
#4 /home/armadabg/web/armadabg.eu/public_html/wp-includes/class-wp-widget.php(394): WC_Widget_Layered_Nav->widget()
#5 /home/armadabg/web/armadabg.eu/public_html/wp-includes/widgets.php(837): WP_Widget->display_callback()
#6 /home/armadabg/web/armadabg.eu/public_html/wp-content/themes/flatsome/woocommerce/layouts/category.php(17): dynamic_sidebar()
#7 /home/armadabg/web/armadabg.eu/public_html/wp-includes/template.php(787): require('...')
#8 /home/armadabg/web/armadabg.eu/public_html/wp-content/plugins/woocommerce/includes/wc-core-functions.php(284): load_template()
#9 /home/armadabg/web/armadabg.eu/public_html/wp-content/themes/flatsome/woocommerce/archive-product.php(27): wc_get_template_part()
#10 /home/armadabg/web/armadabg.eu/public_html/wp-content/plugins/woocommerce/includes/wc-core-functions.php(345): include('...')
#11 /home/armadabg/web/armadabg.eu/public_html/wp-content/plugins/woocommerce/templates/taxonomy-product-cat.php(22): wc_get_template()
#12 /home/armadabg/web/armadabg.eu/public_html/wp-includes/template-loader.php(106): include('...')
#13 /home/armadabg/web/armadabg.eu/public_html/wp-blog-header.php(19): require_once('...')
#14 /home/armadabg/web/armadabg.eu/public_html/index.php(17): require('...')
#15 {main}
  thrown в /home/armadabg/web/armadabg.eu/public_html/wp-includes/functions.php на ред 1144

2023-10-05T12:00:56+00:00 CRITICAL Uncaught TypeError: strstr(): Argument #1 ($haystack) must be of type string, WP_Error given in /home/armadabg/web/armadabg.eu/public_html/wp-includes/functions.php:1144
Stack trace:
#0 /home/armadabg/web/armadabg.eu/public_html/wp-includes/functions.php(1144): strstr()
#1 /home/armadabg/web/armadabg.eu/public_html/wp-includes/functions.php(1217): add_query_arg()
#2 /home/armadabg/web/armadabg.eu/public_html/wp-content/plugins/woocommerce/includes/widgets/class-wc-widget-layered-nav.php(423): remove_query_arg()
#3 /home/armadabg/web/armadabg.eu/public_html/wp-content/plugins/woocommerce/includes/widgets/class-wc-widget-layered-nav.php(187): WC_Widget_Layered_Nav->layered_nav_list()
#4 /home/armadabg/web/armadabg.eu/public_html/wp-includes/class-wp-widget.php(394): WC_Widget_Layered_Nav->widget()
#5 /home/armadabg/web/armadabg.eu/public_html/wp-includes/widgets.php(837): WP_Widget->display_callback()
#6 /home/armadabg/web/armadabg.eu/public_html/wp-content/themes/flatsome/woocommerce/layouts/category.php(17): dynamic_sidebar()
#7 /home/armadabg/web/armadabg.eu/public_html/wp-includes/template.php(787): require('...')
#8 /home/armadabg/web/armadabg.eu/public_html/wp-content/plugins/woocommerce/includes/wc-core-functions.php(284): load_template()
#9 /home/armadabg/web/armadabg.eu/public_html/wp-content/themes/flatsome/woocommerce/archive-product.php(27): wc_get_template_part()
#10 /home/armadabg/web/armadabg.eu/public_html/wp-content/plugins/woocommerce/includes/wc-core-functions.php(345): include('...')
#11 /home/armadabg/web/armadabg.eu/public_html/wp-content/plugins/woocommerce/templates/taxonomy-product-cat.php(22): wc_get_template()
#12 /home/armadabg/web/armadabg.eu/public_html/wp-includes/template-loader.php(106): include('...')
#13 /home/armadabg/web/armadabg.eu/public_html/wp-blog-header.php(19): require_once('...')
#14 /home/armadabg/web/armadabg.eu/public_html/index.php(17): require('...')
#15 {main}
  thrown в /home/armadabg/web/armadabg.eu/public_html/wp-includes/functions.php на ред 1144