I got this error when uploading an add-on.
[phpBB Debug] PHP Notice: in file /dlm/scans/scan_content.php on line 199: in_array() [function.in-array]: Wrong datatype for second argument
[phpBB Debug] PHP Notice: in file /dlm/upload.php on line 1126: Cannot modify header information - headers already sent by (output started at /includes/functions.php:3296)
Hmm, it appears it still uploaded my add-on fine.