Every time I want to preview a topic I get this crazy dialog.
[phpBB Debug] PHP Warning: in file
[ROOT]/includes/functions_messenger.php on line 506: count(): Parameter must be an array or an object that implements Countable
[phpBB Debug] PHP Warning: in file [ROOT]/includes/functions.php on line 1836: Cannot modify header information - headers already sent by (output started at [ROOT]/includes/functions.php:3268)