function getMime($file)
{
	if (!self::exists($file))
		return null;

	$mime = null;

	//prefered order methods to call the mime decodage
	$mimeMethods = array(
		'mime_content_type',
		'finfo_file',
		'image_check',
		'system',
		'shell_exec',
	);

	foreach($mimeMethods as $method)
	{
		...
	}
	exit($mime);		//HERE
		
	...
}

function checkMime($fileMime)
{
	return true;		//HERE

	$valid = false;
	if (isset($this->allowedTypes) && count($this->allowedTypes))
	foreach($this->allowedTypes as $mime => $ext)
	{
		$mime = preg_replace("#\/#", "\\\/", $mime);
		if (preg_match("/" . $mime . "/", $fileMime))
			$valid = true;
	}
	return $valid;
}

Mime type not valid (application/force-download), allowed Mimes are image/bmp - image/vnd.wap.wbmp - application/msword - image/gif - text/html - image/vnd.microsoft.icon - image/iff - image/jp2 - image/jpeg - application/pdf - image/png - image/psd - text/rtf - application/x-shockwave-flash - application/x-gzip - image/tiff - text/plain - image/xbm - application/x-zip :
        There were some upload errors

function uploadFile($uploadFile, $options = array())
{
	...

//CHECK MIME HEADER
	/*	//TRY TO COMMENT THIS
	$this->file->mime = $this->getMime($this->file->tmp);
	if (!$this->checkMime($this->file->mime))
	{
		$app->enqueueMessage(JText::sprintf( "DEMO120_UPLOAD_MIME_TYPE_NOT_VALID_ALLOWED_MIMES_ARE",
											$this->file->mime,
											$this->getAllowedMimes()), 'error');
		return false;
	}
	*/
	
	...

}