preg_replace(): Unknown modifier '0'

Question

The following piece of code always throws the error preg_replace(): Unknown modifier '0'. What could be the reason for that?

$logfile = preg_replace("/\+".preg_quote($dir)."(.*)\+".preg_quote("<>")."/", $log, $logfile);

$logfile is a string looking like this:

14/08/01:Sometext<>14/08/02:Sometext<>

etc

$dir has the format

14/08/01