问题
A GET request is constructed to test the network and it is configurable to purposely wait for 15 minutes within the IIS process before responding.
When the request is issued in Chrome without Fiddler it completes successfully.
However, with Fiddler it is usually either 5 or 10 minutes. When replayed from Fiddler it is 5 minutes (only a few trials so not conclusive).
Within the 10 minute cases, inside the Fiddler Statistics tab is
Request was retried after a Receive operation failed
This related SO answer is for POSTS and a prior Fiddler version.
Why do the 504's only occur when Fiddler is running. Is it Fiddler that is issuing the retry logic--does the browser even see the broken/reset connection?
Fiddler Version: v4.6.2.0
来源：https://stackoverflow.com/questions/38406510/getting-a-504-only-when-fiddler-is-present