The resource could be being blocked by an extension (AdBlock in my case).
The message is there because the request to retrieve that resource was never made, so the headers being shown are not the real thing. As explained in the issue you referenced, the real headers are updated when the server responds, but there is no response if the request was blocked.
我所遇到的此问题的场景:
- 跨域时请求没有发出
- 网络故障(比如我忘记开vpn,导致服务器can't access)导致request timeout ,
- request 被拦截(可能是extension,eg:adblock)
- 缓存(from disk cache)
- from memory cache 没有
