worldpress theme customize issue

hallo WordPress

my issue is i chnage my theme but some issue on my website and appearance – theme and customize butten click then this issue

Fatal error: Uncaught Error: Cannot unset string offsets in /home/u810665089/domains/gadgetsetup.com/public_html/wp-includes/class-wp-customize-widgets.php:1216 Stack trace: #0 /home/u810665089/domains/gadgetsetup.com/public_html/wp-includes/class-wp-hook.php(303): WP_Customize_Widgets->preview_sidebars_widgets('') #1 /home/u810665089/domains/gadgetsetup.com/public_html/wp-includes/plugin.php(189): WP_Hook->apply_filters('', Array) #2 /home/u810665089/domains/gadgetsetup.com/public_html/wp-includes/widgets.php(1035): apply_filters('sidebars_widget...', '') #3 /home/u810665089/domains/gadgetsetup.com/public_html/wp-includes/class-wp-customize-widgets.php(379): wp_get_sidebars_widgets() #4 /home/u810665089/domains/gadgetsetup.com/public_html/wp-includes/class-wp-customize-widgets.php(354): WP_Customize_Widgets->customize_register() #5 /home/u810665089/domains/gadgetsetup.com/public_html/wp-includes/class-wp-hook.php(303): WP_Customize_Widgets->schedule_customize_register(Object(WP_Customize_Manager)) #6 /home/u810665089/dom in /home/u810665089/domains/gadgetsetup.com/public_html/wp-includes/class-wp-customize-widgets.php on line 1216
There has been a critical error on this website. Please check your site admin email inbox for instructions.

Learn more about troubleshooting WordPress.

• This topic was modified 3 years, 2 months ago by Yui.
• This topic was modified 3 years, 2 months ago by Jan Dembowski. Reason: Moved to Fixing WordPress, this is not an Everything else WordPress topic

The page I need help with: [log in to see the link]