Fourth [LWN.net]

Fourth

Posted Dec 16, 2025 23:05 UTC (Tue) by jond (subscriber, #37669)
In reply to: Fourth by mb
Parent article: Mozilla gets a new CEO: Anthony Enzor-DeMeo

> But I'm wondering what Firefox developers actually do when they hit these problems by themselves.
> They must surely see these problems frequently, too, right? I assume they actually all use their own product.

I’m not a Firefox dev, but I am a Firefox user and I never have a problem where a website doesn’t work with Firefox and I have to launch another browser. I’m not sure how common that issue is.

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Fourth

Posted Dec 17, 2025 4:03 UTC (Wed) by xanni (subscriber, #361) [Link] (9 responses)

I've encountered quite a few of these problems, but just to pick one that has a happy ending: Patreon discussion groups used not to load in Firefox, and the image carousels used to display 50% offscreen. Both of those issues persisted for a year or two but have recently been resolved and now work perfectly, though I don't know how much is Firefox improvements and how much is site updates. Patreon is fairly widely used!

Fourth

Posted Dec 18, 2025 11:50 UTC (Thu) by kpfleming (subscriber, #23250) [Link] (8 responses)

Portions of the Monoprice website have been broken in Firefox for a few years at least, but work fine in Chromium.

For example, go to this page - https://www.monoprice.com/product?p_id=2268. After the page has finished loading, click a radio button to switch to a different color. The page content will switch to the new selection, but the 'overlay' which dims the page and shows a spinner never goes away, so you cannot interact with the page. This functionality works as they intended in Chromium and other browsers.

Fourth

Posted Dec 18, 2025 12:46 UTC (Thu) by karkhaz (subscriber, #99844) [Link]

For cases like this, you can right-click on the modal spinner and then press "Inspect" (or "Q"), which displays the developer tools showing you the code for that element. In this case, the class of the modal spinner is "mp-spinner-overlay", so you can use the Stylus extension to remove it from the web page:

.mp-spinner-overlay {
  display: none;
}

This permanently resolves the problem for Monoprice. It's good for modals that break interaction, but also popups like newsletter signup forms, "Sign in with Google/Facebook/etc", and so on.

Fourth

Posted Dec 18, 2025 13:01 UTC (Thu) by farnz (subscriber, #17727) [Link] (4 responses)

This is another case where Firefox 146 from Flathub doesn't reproduce the problem - it works fine for me with, or without, uBlock Origin active on the page.

I wonder if you and mote are using a build from the same supplier? I'm not seeing the reported problems in Firefox from Flathub, and haven't in previous versions, either - which to me suggests that there might be an underlying difference worth tracking down.

Fourth

Posted Dec 18, 2025 13:13 UTC (Thu) by jzb (editor, #7867) [Link] (3 responses)

I'm using the Fedora build of FF and I see the problem as well. If I run a Firefox build from Mozilla, I don't see the problem. Probably worth filing a bug against the package.

Fourth

Posted Dec 18, 2025 13:18 UTC (Thu) by kpfleming (subscriber, #23250) [Link] (1 responses)

Bizarre... I am also using the Firefox build from Mozilla (Debian packages), and I do see the problem. Presumably that means the problem is caused by some interaction between Firefox and the extensions that are loaded, or something else in my profile. I'll try again with a fresh profile to see if it persists.

Fourth

Posted Dec 18, 2025 15:51 UTC (Thu) by johill (subscriber, #25196) [Link]

Indeed. I'm also using Fedora build and it works fine :-)

Most likely different extensions loaded for all of us, and even in the different builds jzb tried?

Fourth

Posted Dec 18, 2025 15:49 UTC (Thu) by rbtree (subscriber, #129790) [Link]

Report these issues to Mozilla when you see them. "Menu: Help → Report broken site", or "hamburger: Report broken site". It takes very little time.

Fourth

Posted Dec 18, 2025 16:54 UTC (Thu) by excors (subscriber, #95769) [Link] (1 responses)

That one happens when Firefox's enhanced tracking protection is set to "strict", and you don't enable "fix minor site issues": https://bugzilla.mozilla.org/show_bug.cgi?id=1962420

You should be able to add per-site ETP exceptions by clicking the shield icon in the address bar. Or turn on "fix major/minor site issues" globally in the settings (which slightly reduces the tracking protection, but appears to fix Monoprice).

Strict mode is advertised as "stronger protection, but may cause some sites or content to break", so the breakage is not considered a Firefox bug - it's a deliberate tradeoff for privacy.

Fourth

Posted Dec 18, 2025 16:57 UTC (Thu) by kpfleming (subscriber, #23250) [Link]

Thank you! I've had ETP enabled for so long I wasn't aware that those 'fix issues' checkboxes even existed.