Magento: Unknown cipher in list: TLSv1 to install new extensions downloader/lib/Mage/HTTP/Client/Curl.php, try changing: $this->curlOption(CURLOPT_SSL_CIPHER_LIST, 'TLSv1'); to $this->curlOption(CURLOPT_SSLVERSION, CURL_SSLVERSION_TLSv1);