User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:92.0) Gecko/20100101 Firefox/92.0

Steps to reproduce:

Use XMLHttpRequest to upload a FormData object containing large file (about 1~2GB) to a misconfigured server (such as nginx with client_max_body_size set too low) OR to a server proxied by a CDN that restricts large uploads, such as CloudFlare (POST requests restricted to 10MB or less).

Actual results:

XHR's onerror callback is called, but no error is filed under the console and the network request in the network request tab never shows a status code response from the server (return is always blank). The status code returned to XHR is 0.

Expected results:

The 413 error should be shown in the network request tab and should be returned to XHR so that the error can be displayed properly to the user/developer.

The Bugbug bot thinks this bug should belong to the 'DevTools::Netmonitor' component, and is moving the bug to that component. Please revert this change in case you think the bot is wrong.

I would like to know why we have this behavior, setting P2 to investigate.

Setting S4 because this is an old behavior.

I'm pretty sure this is the same bug. When the server terminates the connection prematurely, e.g. with a 413, Firefox returns all events as empty fields (status = 0, statusText = "", response = "", ...).

readyState: 4
​​response: ""
​​responseText: ""
​​responseType: ""
​​responseURL: ""
​​responseXML: null
​​status: 0
​​statusText: ""

Here's a reproducible example (including the server in Go; run as go run file.go): https://gist.github.com/binwiederhier/627f146d1959799be207ad8c17a8f345