我也遇到了，花了不少时间在上面，先放弃了。哈哈。
503：网站服务器的问题。
The 503 Service Unavailable error is an HTTP status code that means a website's server is not available right now. Most of the time, it occurs because the server is too busy or maintenance is being performed on it.
A 503 error message can be customized by the website it appears on or the server software that generates it, so how you might see it vary greatly. The 503 Service Unavailable error is an HTTP status code that means a website's server is not available right now. Most of the time, it occurs because the server is too busy or maintenance is being performed on it.
A 503 error message can be customized by the website it appears on or the server software that generates it, so how you might see it vary greatly.