Issue: Undefined variable: startat

Error Info
ErrorException: Undefined variable: startat - vault/core/controller/install/upgradepath/steps/4/0/0/gamma/6/base/vw.php:168 
Generated By: alfa, 1 minute ago

Stack Trace
#0 /vault/core/controller/install/upgradepath/steps/4/0/0/gamma/6/base/vw.php(168): XenForo_Application::handlePhpError(8, 'Undefined varia...', '/home/...', 168, Array)
#1 /vault/core/controller/install/upgradepath/vw.php(57): {closure}(Object(vw_Install_UpgradePath_Controller_XF), true)
#2 /vault/core/controller/cp/install/vw.php(302): vw_Install_UpgradePath_Controller->call(10, true)
#3 /vault/core/controller/cp/install/vw.php(267): vw_CP_Install_Controller->exec_step(Object(vw_Install_UpgradePath_Controller_XF), '4.0.0 Gamma 6', 'C')
#4 /vault/core/controller/cp/install/vw.php(201): vw_CP_Install_Controller->upgrade_type(Object(vw_Install_UpgradePath_Controller_XF), Array, 0)
#5 /vault/core/controller/cp/install/vw.php(71): vw_CP_Install_Controller->upgrade()
#6 /library/vw/XenForo/ControllerAdmin/Wiki.php(107): vw_CP_Install_Controller->execute('10', 'post')
#7 /library/vw/XenForo/ControllerAdmin/Wiki.php(136): vw_XenForo_ControllerAdmin_Wiki->actionIndex()
#8 /library/XenForo/FrontController.php(347): vw_XenForo_ControllerAdmin_Wiki->actionUpgrade()
#9 /library/XenForo/FrontController.php(134): XenForo_FrontController->dispatch(Object(XenForo_RouteMatch))
#10 /admin.php(13): XenForo_FrontController->run()
#11 {main}
Request State
array(3) {
  ["url"] => string(56) " /admin.php?wiki/upgrade"
  ["_GET"] => array(1) {
    ["wiki/upgrade"] => string(0) ""
  }
  ["_POST"] => array(4) {
    ["step"] => string(2) "10"
    ["_xfToken"] => string(8) "********"
    ["submit"] => string(17) "Next Step (10/12)"
    ["do"] => string(2) "10"
  }
}