HTTP status codes / 1xx — Informational
100 Continue
What it means
The server has seen the request headers and tells the client to go ahead and send the body. Used with the Expect: 100-continue header on large uploads.
What causes it
You will rarely see this in devtools — clients handle it silently before sending a large request body.
How to fix it
Nothing to fix. If an upload stalls after 100, the follow-up response (413, 401) is the one that matters.