Firefox snap version in 21.10 CORS problem

M_breeb

2/21/23, 6:37 AM

After upgrading to 21.10, I run into a CORS problem with an HTML page that uses Javascript fetch() to GET a page from a server. Same page does not have problems with Chromium under 21.10 (or Firefox or Safari on OSX).

Looking at the inspector, the difference seems to be that "Snap Firefox":

has a different value for the REFERER header (it is shortened to http://127.0.0.1:5000/ instead of http://localhost:5000/resource/527706d7e339cac99572cad1b7b789c8 in the working browsers);
there is an ORIGIN header with value http://127.0.0.1:5000, which is absent in the working browsers

Anyone has any ideas why Snap Firefox is doing this and how it can be solved?

UPDATE / ANSWER:

tl/dr; it boils down to the difference between 127.0.0.1 and localhost, but with a twist.

First of all, the CORS error only occurs when 127.0.0.1 and not with localhost. I've been using localhost in development, so I wasn't aware of this distinction.

Second, Snap Firefox doesn't like "localhost:5000". That's why I found out the page wasn't working. It really wants you to add the protocol -> "http://localhost:5000" works. Apparently, there is no rule that says that localhost must resolve to http://localhost, so Snap Firefox is not wrong.

However, Firefox on OS X does accept "localhost:5000" (by automagically prefixing http://) - just like Safari on OS X or Chromium on Ubuntu. It seems Snap Firefox is the only one out there not adding the http:// string. And I am quite sure that this is a change between Ubuntu 20.04 and 20.10.

For the sake of consistency, I would argue that Snap Firefox should revert to the old behaviour (which is consistent with OS X Firefox), but there are probably good reasons for not doing that.

164

0 + 0

firefox

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21.10

Archisman Panigrahi

2/21/23, 7:04 AM

As a workaround, switch to the .deb version. `sudo snap remove firefox && sudo apt install firefox`.

matigo

2/21/23, 7:29 AM

If this is a website that you created, this would be an opportune time to update it to follow proper CORS policies, as it's only a matter of time before all browsers block cross-domain Ajax requests that do not adhere to the HTTP standards

N0rbert

2/21/23, 8:34 PM

Does this answer your question? [21.10 Firefox Missing Profiles](https://askubuntu.com/questions/1369493/21-10-firefox-missing-profiles)

Elon Musk

I sit in a Tesla and translated this thread with Ai:

EN: Firefox snap version in 21.10 CORS problem

TH: Firefox snap เวอร์ชัน 21.10 CORS ปัญหา

RO: Versiunea Firefox snap în 21.10 problemă CORS

RU: Snap-версия Firefox в проблеме 21.10 CORS

VI: Phiên bản snap của Firefox trong sự cố CORS 21.10

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