Thread: Classiipress 3.6.1 / Wordpress 5.3.2 / Refine Results not Working

Classiipress 3.6.1 / Wordpress 5.3.2 / Refine Results not Working

Hi there, am using the old ClassiPress Version 3.6.1 and do not want to upgrade to the new version unless I am forced to do so.
the "refine results" does not work (http://justcanvey.co.uk/ad-category/places-to-drink/).
Tick either children allowed yes or children allowed no and both return no results.
My webspace provider says the error log had the following :-

PHP Warning: preg_match() expectsparameter 2 to be string, array given in/home/sites/justcanvey.co.uk/public_html/wp-includes/class-wp-block-parser.php on line 417

PHP Warning: strlen() expects parameter1 to be string, array given in/home/sites/justcanvey.co.uk/public_html/wp-includes/class-wp-block-parser.php on line 489

Please advise what the issue could be.