I am using a windows-1254 based translation file and my blog character encoding is windows-1254. After uploading an image by using the media uploader, when I click on "Show", character encoding of image property text like "caption", "link url" etc. are wrong. They show ? characters on special characters. I saw that it is because AJAX does not send the encoding type information when updating the page, so encoding becomes wrong. To solve this problem it is necessary to change the line
header('Content-Type: text/plain');
to
header('Content-Type: text/plain; charset=' . get_option('blog_charset'));
in the file wp-admin/async-upload.php file. More exact place of the line is
// Flash often fails to send cookies with the POST or upload, so we need to pass it in GET or POST instead
if ( empty($_COOKIE[AUTH_COOKIE]) && !empty($_REQUEST['auth_cookie']) )
$_COOKIE[AUTH_COOKIE] = $_REQUEST['auth_cookie'];
unset($current_user);
require_once('admin.php');
header('Content-Type: text/plain');
must be
// Flash often fails to send cookies with the POST or upload, so we need to pass it in GET or POST instead
if ( empty($_COOKIE[AUTH_COOKIE]) && !empty($_REQUEST['auth_cookie']) )
$_COOKIE[AUTH_COOKIE] = $_REQUEST['auth_cookie'];
unset($current_user);
require_once('admin.php');
header('Content-Type: text/plain; charset=' . get_option('blog_charset'));
