Problems posting new item?

Hello,

I’ve got the below error when post new item, even in Preview, anyone could help to advice what has been wrong? thx!

Fatal error: Allowed memory size of 16777216 bytes exhausted (tried to allocate 1966080 bytes) in /var/www/phpbb/includes/utf/data/utf_nfkc_qc.php on line 2

thanks
jackyjoy