In latest WordPress versions starting from 3.6.1, .swf extention is no longer allowed by default. WordPress has disabled swf file uploads for security reasons. Please refer to http://codex.wordpress.org/Version_3.6.1 for more details.

But still if you want to uload the swf file as a banner on your site – please do below mentioned changes.

Open functions.php file from WPAdCenter folder and add new function to it

if ( !function_exists( ‘WPAdCenter_addSwf’ ) )
{
function WPAdCenter_addSwf($mimes) {
if ( function_exists( ‘current_user_can’ ) )
$unfiltered = $user ? user_can( $user, ‘unfiltered_html’ ) : current_user_can( ‘unfiltered_html’ );
if ( !empty( $unfiltered ) ) {
$mimes[‘swf’]= ‘application/x-shockwave-flash’;
}
return $mimes;
}
add_filter(‘upload_mimes’,’WPAdCenter_addSwf’);
}

This will solve the problem. If still you are facing any issue, please contact us