2000446 - screen flashes before and after the website loads

Status: RESOLVED DUPLICATE of bug 1991553

(Firefox :: Theme, defect, P3)

Description

[negocjator7]

User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:147.0) Gecko/20100101 Firefox/147.0

Steps to reproduce:

After updating Nightly to a new build on Thursday November 13th, the screen began to flash before browser started to load a webpage. Also opening new tab started with a flash. Thankfully to my eyes the flash was not white, but gray.

Actual results:

The screen flickers before loading a webpage and after opening new tab.

Expected results:

The aforementioned event should not occur.

Comment 1

[BugBot [:suhaib / :marco/ :calixte]]

The Bugbug bot thinks this bug should belong to the 'Firefox for Android::General' component, and is moving the bug to that component. Please correct in case you think the bot is wrong.

Comment 2

[Mimi Jung]

Hi negocjator7, sorry you're experiencing this. Would you be able to go into troubleshooting mode (about:support) and can you copy & paste the info in about:support so we can get more insight into what might be happening? Any chance you have a screen recording as well?

Comment 3

[negocjator7]

Attachment: raw-dump-of-about-support

Comment 4

[negocjator7]

Attachment: raw-dump-of-about-support-ts-mode

Comment 5

[negocjator7]

I uploaded two attachments: first is about:support dump in Normal Mode (saved as an “raw-dump-of-about-support” attachment), the second one is a raw dump of about:support in Troubleshooting Mode–saved as “raw-dump-of-about-support-ts-mode”.

Comment 6

[negocjator7]

Attachment: Screencast 2025-11-29 16:14:50.mp4

This a screencast of a problem.

Comment 7

[negocjator7]

The problem persists also in Troubleshooting Mode (with hardware accel disabled that is).

Comment 8

[negocjator7]

I tried also CSS hack like that also to no avail.

Comment 9

[Timothy Nikkel (:tnikkel)]

This looks a lot like bug 1991553, it might be the same bug.

Comment 10

[Ina Popescu, Desktop QA]

I can reproduce this in Nightly 148.0a1 and Firefox 146.0 on Ubuntu 22.04 using the same STR from Bug 1991553. @negocjator7, could you check if your about:preferences#home settings match the ones mentioned in that bug? It would help confirm if this is the same issue.

Comment 11

[negocjator7]

(In reply to Ina Popescu, Desktop QA from comment #10)

I can reproduce this in Nightly 148.0a1 and Firefox 146.0 on Ubuntu 22.04 using the same STR from Bug 1991553. @negocjator7, could you check if your about:preferences#home settings match the ones mentioned in that bug? It would help confirm if this is the same issue.

When I change the about:blank in about:preferences#home to about:newtab, the screen stops flickering upon opening new tab. But. It still flashes when loading a website. I attached a screencast file to document this.

Comment 12

[negocjator7]

Attachment: After changing new tab to about:newtab flickering persists upon loading webpage.

Comment 13

[Erich Gubler [:ErichDonGubler] (he/him)]

This seems severe enough to make people ditch using Firefox, so I'm tentatively classifying as S2, and bumping into gfx-triage.

Comment 14

[negocjator7]

What’s interesting is when I download a file by opening the link to download in new tab, the screen remains in that flash state. Video file depicting this attached.

Comment 15

[negocjator7]

Attachment: Download in the new tab: flash “freezes” still.

Comment 16

[negocjator7]

Update: the glitch crept to Beta branch (tested on 147b2). Currently only Release is unaffected. Fun fact: the latest Waterfox “inherited” the glitch too.

Comment 17

[Ina Popescu, Desktop QA]

negocjator7, could you try reproducing the issue with the default GNOME appearance? Testing with the default theme will help see if the flicker is related to the custom Midnight-Green / Adwaita theme. Thank you.

Comment 18

[Brad Werth [:bradwerth]]

(In reply to Ina Popescu, Desktop QA from comment #10)

I can reproduce this in Nightly 148.0a1 and Firefox 146.0 on Ubuntu 22.04 using the same STR from Bug 1991553. @negocjator7, could you check if your about:preferences#home settings match the ones mentioned in that bug? It would help confirm if this is the same issue.

Great that you can reproduce. Would you please run a mozregression?

Comment 19

[Ina Popescu, Desktop QA]

Bug 2000446 looks like a duplicate of Bug 1991553 as mentioned in Comment 9. I was able to reproduce the issue from Bug 1991553 by setting the default new tab page from “Firefox Home” to about:blank with the Dark theme enabled. I couldn’t see the additional issues described by reporter here, like flashing on page load or when opening a download link.
I started looking for a regression range for Bug 1991553, but it turns out the issue is already present in older versions, such as Firefox 123.0, so this is not a recent regression.

Comment 20

[:hello]

(In reply to negocjator7 from comment #0)

User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:147.0) Gecko/20100101 Firefox/147.0

Steps to reproduce:

After updating Nightly to a new build on Thursday November 13th, the screen began to flash before browser started to load a webpage. Also opening new tab started with a flash. Thankfully to my eyes the flash was not white, but gray.

Actual results:

The screen flickers before loading a webpage and after opening new tab.

Expected results:

The aforementioned event should not occur.

Looks alot like this Bug aswell Bug 1997751
Basically same time frame.

Comment 21

[negocjator7]

(In reply to Ina Popescu, Desktop QA from comment #17)

negocjator7, could you try reproducing the issue with the default GNOME appearance? Testing with the default theme will help see if the flicker is related to the custom Midnight-Green / Adwaita theme. Thank you.

I changed theme for default Adwaita. The problem persists. Attached video file Screencast 2025-12-13 16:31:44.mp4

Comment 22

[negocjator7]

Attachment: Nightly running with default Adwaita theme.

Comment 23

[negocjator7]

I came to think my issue may be connected with my system, which is old Ubuntu 18 Bionic, but still supported by Canonical through ESM (Extended Security Maintenance) at least till 2028. Most new programs don’t run on it because of outdated Gnu C Library (glibc), but Firefox/Thunderbird Mozilla builds still work.

Comment 24

[negocjator7]

Anyway the problem is not so critical to me, the flashes being gray, not white, so if fixing that is too much trouble I wouldn’t bother that much.

Comment 25

[Bob Hood [:bhood]]

Flagging as stalled until we have cycles available to investigate.

Comment 26

[Brad Werth [:bradwerth]]

Like the See Also Bug 1991553, this is an issue with Themes.

Comment 27

[Jules Simplicio [:jules]]

We're marking as duplicate as we have an older bug on this where we're also discussing the background color being slightly different.
We can handle it on that bug.

Comment 28

[BugBot (nomail) [:suhaib / :marco/ :calixte]]

Since the bug is closed, the stalled keyword is now meaningless.
For more information, please visit BugBot documentation.