prestashop升级后在后台登录addons后会出现空白，打开debug模式后出现

 Fatal error: Undefined class constant 'MODE_CONTRIB' in/classes/controller/AdminController.php on line 405

只需要注释掉// Set context mode下面的语句就可以了，不知道是bug还是因为哪一些模块引起的

// Set context mode
        /*
		if (defined('_PS_HOST_MODE_') && _PS_HOST_MODE_)
		{
			if (isset($this->context->cookie->is_contributor) && (int)$this->context->cookie->is_contributor === 1)
				$this->context->mode = Context::MODE_CONTRIB_HOST;
			else
				$this->context->mode = Context::MODE_HOST;
		}
		elseif (isset($this->context->cookie->is_contributor) && (int)$this->context->cookie->is_contributor === 1)
			$this->context->mode = Context::MODE_CONTRIB;
		else
			$this->context->mode = Context::MODE_STD;
        */

		$this->context->smarty->assign(array(
			'context_mode' => $this->context->mode,
			'logged_on_addons' => $this->logged_on_addons,
		));