HTMX POST request never ends when backend returns error during upload in form

[Thomasedv]

This may just be stupidity on my side, all web stuff is new to me.
Long story short, I am making website for fun, and use HTMX and actix-web(Rust) for the first time.

I am uploading a file and when the filesize limit is reached, the backend throws a 500 Error(for now) that I can see logged on my server, but HTMX never seems to pick up on this causing the POST request to just eternally hang.

This might not even be a HTMX thing, maybe it's Firefox for all I know. But I'm looking at the network tab in my browser and seeing the POST request not having a status code, not even after killing the backend...

I just tried htmx v2, but I also used v1.x, but both appear to do the same.

Happy to share more code, there is some scripts to handle drag and drop but nothing that is throwing an error, and just a progress bar update that actually even hit a breakpoint. Here is the actual HTML form snippet though:

<div class="upload-container">
    <form id="form" hx-encoding="multipart/form-data" hx-post="/upload-article">
        <label for="file-input" class="upload-box">
            Click or Drag a file to upload
        </label>
        <input type="file" name="file" id="file-input" hidden>
        <button type="submit">Upload</button>
        <progress id="progress" value="0" max="100"></progress>
        <div id="error-message" style="display:block; color: red;"></div>
    </form>
</div> 

How Firefox shows the tab after 5 minutes of me writing this, and backend dead.

Backend log entry:

[Runtime] INFO actix_web::middleware::logger: 127.0.0.1 0.006709s "POST /upload-article HTTP/1.1" 500 14 http://127.0.0.1:8000 upload

Anyone got any clue, or have any pointers for me to find out why this happens? Am I just incorrectly handling "cancelling" a upload server side? The current solution is manual, but before this had some more magic code that threw a Bad Request and caused the same issue.

[Thomasedv]

Nevermind.

Turns out, the actix-web server is the one to blame according to this: actix/actix-web#3152