Hi paulo,
I have run across this also. Look in the file 'update_to_latest.php', or what ever it is. At about line 45 you will find this
CODE
$phpbb_root_path = './../';
replace it so it looks like this
CODE
$phpbb_root_path = '';
(That is 2 single apostrophe’s, not one quote symbol)
Then call for this page in your browser again to run it, then delete or re-name it so it cannot be ran again.
HTH, Tom