The config page being blank after a upgrade can happen
because Magento turned off SSLv3 on Magento Connect. The
solution for that is found here Magento
1.9.2 Unknown cipher in list: TLSv1
 In file
downloader/lib/Mage/HTTP/Client/Curl.php change the code

$this->curlOption(CURLOPT_SSL_CIPHER_LIST, 'TLSv1'); 
to
if(isset($var)){
   $this->curlOption(CURLOPT_SSL_CIPHER_LIST, 'TLSv1');
}

Only after this change can the last updates be done. In my
clients case there where 4 core files not updated.

Read these posts.