I have a WordPress website that was recently moved to a new website hosting account. However when I try to login to the WP admin panel I am presented with the below error message.

The error message I am getting is

Uncaught ArgumentCountError: Too few arguments to function _x(),    
1 passed in /wp-content/themes/**/library/custom-post-types.php on line 9 
and at least 2 expected in /wp-includes/l10n.php:347 Stack trace: #0 
/wp-content/themes/**/library/custom-post-types.php(9): _x('Testimonials') #1 
/wp-includes/class-wp-hook.php(288): testimonials_init('') #2 
/wp-includes/class-wp-hook.php(312): WP_Hook->apply_filters(NULL, Array) 
#3 /wp-includes/plugin.php(478): WP_Hook->do_action(Array) 
#4 /wp-settings.php(523): do_action('init') #5 /wp-config.php(89): 
require_once('/var/www/...') #6 /wp-load.php(37): 
require_once('/var/www/...') #7 /wp-blog-header.php(13): require_once('/var/www/...') 
#8 /index.php(17): require('/var/www/...') #9 {main} thrown in /wp-includes/l10n.php on line 347