i getting this error code on my site that uses prosite

i getting this error code on my site that uses prosite plus my check out is gone. Fatal error:

Uncaught exception 'Exception' with message 'Stripe needs the Multibyte String PHP extension.' in /home/geturwebsite/public_html/wp-content/plugins/pro-sites/pro-sites-files/gateways/gateway-stripe-files/lib/Stripe.php:13 Stack trace: #0 /home/geturwebsite/public_html/wp-content/plugins/pro-sites/pro-sites-files/gateways/gateway-stripe.php(21): require_once() #1 /home/geturwebsite/public_html/wp-content/plugins/pro-sites/pro-sites-files/lib/ProSites/View/Gateways.php(193): ProSites_Gateway_Stripe->__construct() #2 [internal function]: ProSites_View_Gateways::render_tab_stripe() #3 /home/geturwebsite/public_html/wp-content/plugins/pro-sites/pro-sites-files/lib/ProSites/Helper/Tabs.php(90): call_user_func(Array) #4 /home/geturwebsite/public_html/wp-content/plugins/pro-sites/pro-sites-files/lib/ProSites/Helper/Tabs/Gateways.php(27): ProSites_Helper_Tabs::render_child('ProSites_Helper...', 'ProSites_View_G...', Array, Array, Array) #5 /home/geturwebsite/public_html/wp-content/plugins/pro-sites/pro-sites-files/lib in /home/geturwebsite/public_html/wp-content/plugins/pro-sites/pro-sites-files/gateways/gateway-stripe-files/lib/Stripe.php on line 13

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