Firefox Community Forum

Best regards,

At the beginning of 2025, I created a private theme and installed it locally (Windows 10), consisting of a manifest.json and a GIF file. It worked perfectly. Now, on Windows 11, I'm trying to use the theme again, but when I upload the file (.zip or .xpi — via about:addons -> Install Add-on From File), I always get the message that the file is corrupted. However, if I test it temporarily under about:debugging, it works immediately without any issues.

I would really appreciate a solution! <3

I’m at my wits’ end with this. Firefox keeps forcing a system-synced theme at launch, and it flat-out refuses to respect the settings I’ve configured — both in about:config and via a custom user.js file.

Here’s what I’ve tried:

• Set layout.css.prefers-color-scheme.content-override to 0 in about:config → it reverts back to 2 after every restart.

• Created a user.js with user_pref("layout.css.prefers-color-scheme.content-override", 0); → completely ignored.

• Disabled all sync options, including themes.

• Verified that no active studies are interfering.

• Double-checked that I’m not syncing across devices.

• Tried applying a specific theme and setting it manually — still overridden at launch.

No matter what I do, Firefox insists on syncing the theme to the system’s dark/light setting. I want my browser theme independent from the OS — period.

Is there a deeper setting I’m missing? A hidden override? Some service that’s reapplying the system setting post-launch? This feels like Firefox is actively fighting me — and it's infuriating.

Would appreciate any insight or workaround. I just want full manual control over my theme. Why is that so hard?

I am unable to remove add on themes. The remove button is not provided. Only manage which enables the theme. I do not want these themes and want them removed now. mac ios

you are repeating old mistakes. You have become worse than Microsoft. Firefox is not remembering open tabs again. I have supported your Firefox until now but enough is enough.

I have literally over 200 tabs open at a time and recover them every time I reboot Firefox, but they are very disorganized. Is there a good way to organize them, for example, group related tabs together?

I recently updated to Firefox 135.0 on MacBook Pro, Catalina, OS 10.15.7 In the past, with multiple Firefox windows open & multiple tabs open in each, when restarting, "reopen pages on startup" selected, system loaded & ready to go, I'd find all windows, tabs & history available upon launching Firefox. Since update to 135.0, shut down & restart, launch Firefox and I find a single blank new window, no multiple windows, no tabs, no history. I've tried to find [Settings] to make everything come back - no joy, to no avail. Suggestions? Help? Thanks, JS

Good Day,

I am leaving Brave as my default browser for Firefox.... Brave is good, just would prefer Firefox. I used to love it.

The problem is...I have a theme on Brave and Chrome that I love dearly. Is there a way to bring that theme to Firefox? I tried using Firefox Color, but it looked awful.

PS: I am the tech Village Idiot so please talk to me in that vein ;)

Thank you and Warmest Regards, Alisa (Stormwolfe)

I set a theme with https://addons.mozilla.org/en-US/fire.../firefox-color/(Firefox Color), I tried changing the theme in settings to light or dark but neither work. I'm wondering if there are other ways to do so in Firefox that I could try. I'm on zen browser which is why it may not have worked.

I can not get rid of the pink background in the address bar, search box or background space of yahoo mail. I can not find the revert to default theme as previous post from several years ago suggested as a solution.