Issue: Failure on upgrading from XF 1.1.5 to XF 1.2rc2 with same VW

An exception occurred: String could not be parsed as XML in /var/www/html/forum/vault/core/controller/install/common/xf.php on line 290
SimpleXMLElement->__construct() in /var/www/html/forum/vault/core/controller/install/common/xf.php at line 0
vw_Install_Common_Controller_XF->do_template_modifications() in /var/www/html/forum/vault/core/controller/install/upgradepath/steps/final/xf.php at line 143
{closure}() in /var/www/html/forum/vault/core/controller/install/upgradepath/vw.php at line 57
vw_Install_UpgradePath_Controller->call() in /var/www/html/forum/vault/core/controller/cp/install/vw.php at line 264
vw_CP_Install_Controller->exec_step() in /var/www/html/forum/vault/core/controller/cp/install/vw.php at line 177
vw_CP_Install_Controller->upgrade() in /var/www/html/forum/vault/core/controller/cp/install/vw.php at line 69
vw_CP_Install_Controller->execute() in /var/www/html/forum/vault/cp/global.php at line 72
require_once() in /var/www/html/forum/vault/install/index.php at line 37