Diễn đàn hỗ trợ Firefox

Summary: Uploading a file to a custom webapp with Chromium (Edge) works but consistently fails in Firefox. In Firefox the request is created, and times out. The server receives no file and logs “missing file.” The same webapp code is running on both Chromium and Firefox.

Environment:

• Next.js app (pages/api route)
• Endpoint: POST /api/file-upload
• Client: fetch(url, { method: "POST", body: FormData, credentials: "include" })
• Server: export const config = { api: { bodyParser: false } } + multipart parsing (formidable)
• Edge/Chromium: Version 141.0.3537.85
• Firefox Version 147.0.3 (64-bit)
• OS: Ubuntu 22 / Linux

Steps to reproduce:

1. Create a FormData object and append a local file:

  const fd = new FormData();
  fd.append("template", file, file.name);
  fetch(`/api/file-upload`, {
    method: "POST",
    body: fd,

1. In Edge/Chrome, upload succeeds. Server receives multipart body and parses the file. Actual behavior in Firefox:

• Transferred: 0 B
• No response status/body
• Client times out (Upload times out)
• File upload request received
• No bytes read server‑side.

Evidence:

• Edge request logs:
  • content-type: multipart/form-data; boundary=----WebKitFormBoundary...
  • bytesRead ~1.69MB
• Firefox request logs:
  • Transferred 0 B
  • File upload missing file field

Notes:

• Client FormData is valid; we log file.name and file.size right before fetch.
• There is a CSP report‑only warning (frame‑ancestors) when using a fallback iframe approach, but we are not using iframe in the failing case.

Question: Is there a known issue where Firefox blocks or fails to send and multipart/body can be stripped before it leaves the browser? Is there a recommended workaround that does not rely on browser sniffing?

Moderator note: This question has been edited to correct the formatting.

good morning,

I am having problems using a third-party website, playing chess, and one of the functions on their website is not available to me because I keep getting an error message. they have a forum on which I am discussing this issue with one of their Mod's, and he seems to be under the impression it has something to do with my Browser (Firefox 115.32.0esr) storing site data, and that the file in which this is stored has become corrupted in some way. I have no idea how he arrived at this conclusion but that is what he said.

I assured him that, "in Firefox, under <Privacy and Security>, in <Cookies and Site Data>, there is an option marked: "Delete cookies and site data when Firefox is closed." this has a tick box next to it and on my computer this has been selected for about the last five or six years. the browser does not retain site data or cookies and deletes them each time it closes. when I follow the instructions you linked to, and click <Manage Data>, there is no data to manage. it does not exist."

however, he replied to this that: "I don’t think that setting deletes Local Storage, though I’m not 100% certain."

one observation I make is that when I open the <Cookies and Site Data> <Manage Data> dialogue, the websites I have visited in the current session are listed. this data therefore does exist, and there must therefore be a file, even if only temporarily, containing this data. my question is about what exactly happens to this file when I close the session.

1) is the file emptied of data, but still exists as a file.

or

2) is the file physically deleted so that it no longer exists.

if, after the session, I reopen the browser and select the <Clear Data> dialogue and click <Clear> does this simply empty the file or does it physically delete the file. if the file still exists, is there any way to ensure that it is physically deleted in order to confirm that it is not corrupted in some way?

thank you.

This has happened several times in the last 4 months or so, it had never happened prior to that and I've used Firefox for years. It now occurs when I open Firefox after my computer has either been shutdown, or the computer does a restart. I am signed in to my Mozilla account.

Just wanted to ask about the potential for other Ai providers - Duck.ai being the key one missing.

Is there a possibility of local instances being a feature? Whether it's just hosted locally (not a function or component of Firefox itself) or a Mozilla specific model that's locally run?

Moderator note: This question has been edited to correct the link.

Why has Mozilla decided to COMPLETELY IGNORE security settings applied to PDF documents? I have a number of PDFs secured so as to prevent the ability to print or copy text. When opened with Firefox, all of these settings are ignored.

When I log in to my Apple tv account on the Firefox browser, it comes up, but won't play the selected program. All other streaming services I subscribe to work fine on Firefox, as did Apple tv until this week. If I try running Apple tv on Google chrome on the same lap top, it works fine too. Ditto on my iPhone using Safari. I'd prefer staying on Firefox to stream Apple tv, but can't make it work at the present time. Can you help?

После включения ПК бывает, что я не могу ввести текст в браузере.(как буд-то включается режим только для чтения, что не позволяет текст ввести). горячие клавиши работают, но текст не вводиться только в браузере. Оно само по себе проходит. Как это исправить?