当服务器不可用时，我尝试发送请求时遇到了同样的问题.然后，当服务器恢复活动时-发生此错误.

I had the same problem, occurred when I tried to send request when server was unavailable. Then when server comes alive - this error occured.

这对我有帮助:

URLCache.shared.removeAllCachedResponses()