基础连接已经关闭: 服务器关闭了本应保持活动状态的连接

手机自动化过程中提示：xbot.errors.UIAError: A exception with a null response was thrown sending an HTTP request to the remote WebDriver server for URL http:/网址/. The status of the exception was KeepAliveFailure, and the message was: 基础连接已经关闭: 服务器关闭了本应保持活动状态的连接。是怎么个情况啊