fatal error message

Hi – I just switched themes and now am getting this message across my home page – ABOVE – the start of the new theme… I have deleted all old files and deactivated all plugins…

Warning: preg_split() expects parameter 2 to be string, object given in /home/example/domains/examplesite.com/public_html/wp-includes/formatting.php on line 34

Your help is greatly appreciated.