Invalid request, be sure to set all necessary keys.

login to your server (i am assuming SSH to a Unix box)
cd $whatever_your_doc_root_is
find . -name '*.php'
# this should give you a biiiiig list of files
php -l $afile
# should report any errors

# edit the file you just compiled to have the following at the top
# this is untested, but looks correct...

error_reporting(-1);
# bool handler ( int $errno , string $errstr [, string $errfile [, int $errline [, array $errcontext ]]] )
function h1($errno, $errstr, $errfile, $errline) {
     echo("$errfile#$errline: [$errno]$errstrn");
     return true;
}
set_error_handler('h1');

for x in `find . -name '*.php' ` do php -l $x; done