Uploadify: show error message from HTTP response

Take a look at these two posts in the uploadify forum on how to handle errors

onError to display what’s happening
and
Upload script error reporting

there is a lot of useful info in there ..

Update

The following seems to do the trick for me ..

'onComplete': function(a, b, c, d, e){
                    if (d !== '1')
                        {
                        alert(d);
                        }
                    else
                        {
                        alert('Filename: ' + c.name + ' was uploaded');
                        }
                  }

coupled with this version of the uploadify script

<?php

    if (!empty($_FILES)) 
    {
        $tempFile = $_FILES['userfile']['tmp_name'];

        $targetPath = $_SERVER['DOCUMENT_ROOT'] . $_REQUEST['folder'] . "https://stackoverflow.com/";
        $targetFile =  str_replace('//',"https://stackoverflow.com/",$targetPath) . $_FILES['userfile']['name'];

        move_uploaded_file($tempFile,$targetFile);

        switch ($_FILES['userfile']['error'])
        {     
            case 0:
             $msg = ""; // comment this out if you don't want a message to appear on success.
             break;
            case 1:
              $msg = "The file is bigger than this PHP installation allows";
              break;
            case 2:
              $msg = "The file is bigger than this form allows";
              break;
            case 3:
              $msg = "Only part of the file was uploaded";
              break;
            case 4:
             $msg = "No file was uploaded";
              break;
            case 6:
             $msg = "Missing a temporary folder";
              break;
            case 7:
             $msg = "Failed to write file to disk";
             break;
            case 8:
             $msg = "File upload stopped by extension";
             break;
            default:
            $msg = "unknown error ".$_FILES['userfile']['error'];
            break;
        }
    }
    if ($msg)
        { $stringData = "Error: ".$_FILES['userfile']['error']." Error Info: ".$msg; }
    else
        { $stringData = "1"; } // This is required for onComplete to fire on Mac OSX
    echo $stringData;
?>