As reported on https://www.reddit.com/r/firefox/comments/eagm0o/since_firefox_71_ive_been_getting_black_boxes_on/

Since Firefox 71, I've been getting black boxes on pages randomly.

Moving my mouse around fixes them all instantly.

User reports that disabling WebRender via gfx.webrender.force-disabled resolves the issue.

Does this reproduce on Nightly for them?

Not so far, but it's an intermittent issue.

Possibly a picture caching bug, Glenn?

I've asked the user on reddit if setting gfx.webrender.picture-caching=false makes a difference.

Will probably be hard to investigate without being able to reproduce. Does anyone in the team have this hardware?

Seems like this could be similar to other bugs we've been having reported. We have been testing on similar hardware in Toronto but don't yet have STR

Yep, it seems similar to the other bugs in wr-ui-glitch. Still haven't managed to repro anything similar yet :(

There is a new flag available in the next nightly build (and only available in nightly builds) called gfx.webrender.panic-on-gl-error that can be set in about:config. After changing this value, a restart is required before it takes effect.

When this flag is set, any time the GPU driver reports a GL error, we will detect this and panic (controlled crash) the entire GPU process. It shouldn't take the entire browser down, just the GPU process (I believe the GPU process is enabled on Windows and Linux, not sure about Mac).

If you see the bug occur while that is active, and then restart the browser, the logs from the GL error should be visible in about:support.

If you see the glitch occur while that option is active, we can infer a few things:

• If there is no GPU process crash / output logs, then no GL error is being reported (likely signals a driver bug).
• If there is a GPU process crash, the logs should give us a clue as to what is occurring (even if nothing is logged, it would still be a clue there is a GL error occurring).

Also, airphforce can you try restoring the 3d settings under global settings in the "NVIDIA Control Panel" application to see if that helps?

I have done so and am now on nightly. Sorry about the delays. Will report back with findings.

Oh and

gfx.webrender.panic-on-gl-error is set to true.

Sorry about the delay! I will report back with findings.

Another question that would be helpful to know - are you using multiple monitors?

That's a negatory good buddy

Also please bear with me on this I have really no idea what im doing when it comes to debugging and whatnot.

airphforce - one more request for today :)

when you encounter the problem, could you try pressing Ctrl-Shift-3 ? This should generate a wr-capture folder in your AppData\Local windows folder (for example C:\Users\you\AppData\Local\wr-capture). Then please zip and share the contents of that. This again will help us figure out what is going on

Thanks for your help and patience as we try to sort through this tricky bug! We appreciate it.

Sure! Keep in mind im using the nightly as my current browser, will ctrl-shift-3 reveal any personal info if im on my facebook or portfolio or whatever?

Whoops I accidentally cleared the request. I told you im new! Please re-add the needinfo.

It could reveal rendered pieces of websites, but not personal info such as account information, etc. If you are able to get a capture, you can always send it directly to me (jbonisteel@mozilla.com) instead of posting it on Bugzilla.

Sure.

I've been on nightly and no sign of the bug yet. Annoying, or good as perhaps it's been fixed? I'll keep you posted.

Have been on nightly consistently for 4 days. Not seen it once, which is very very unusual.

I'm guessing it got fixed at some point.

Another person seeing this: https://www.reddit.com/r/firefox/comments/efxssg/when_i_visit_sites_i_get_those_black_bars_to/ - about:support attached in next comment.

I am curious if you have seen this again recently?

On nightly, no. On the normal firefox, yes.

This is coming up again. More people posting their debug info in this thread;

https://www.reddit.com/r/firefox/comments/ekak8g/weird_rendering_on_firefox_why/?st=k51fcpln&sh=af093a7e

If you see this again in Release, can you take more screenshots and send them our way? The more screenshots the better!

Sure!

72.0.1.

Black squares appeared for a moment, wasn't able to get a screenshot.

Would like to confirm that this is still happening.

https://i.imgur.com/4d4sT7d.png

Another instance, reported here: https://www.reddit.com/r/firefox/comments/ewtvcd/does_this_happen_to_you/

I've also been experiencing this bug on Windows 10 64 bit with an Nvidia GTX 1080 ti on Firefox 72, happens about once a day.

We suspect there are two different bugs happening and I have made an additional meta bug to keep track of the details.

• the wr-ui-glitch bug seems to be when bits of the text/ui glitch out, users seem to report that mousing over the area brings the text back
• wr-blackboxes bug seem to be when parts of the page are obscured by black boxes and rectangles.

Given the differences, it is worth tracking separately.

You mentioned that you see the issue with the black boxes about once a day. Have you noticed if there are particular websites where this seems to happen more frequently? Any common steps to reproduce you have found so far?

Would you be willing to try out Firefox Nightly for a week or so and let us know if it happens there: https://www.mozilla.org/en-CA/firefox/channel/desktop/ ?

yoasif - just pinging you so you see the distinction between the two different bugs. If you see more reports of people talking about the black boxes, can you please block them against wr-blackboxes? Thank you for your help!

(In reply to Jessie [:jbonisteel] plz needinfo from comment #34)

We suspect there are two different bugs happening and I have made an additional meta bug to keep track of the details.

• the wr-ui-glitch bug seems to be when bits of the text/ui glitch out, users seem to report that mousing over the area brings the text back
• wr-blackboxes bug seem to be when parts of the page are obscured by black boxes and rectangles.

Given the differences, it is worth tracking separately.

Both happen at once. I posted a screen in this topic;

https://i.imgur.com/4d4sT7d.png

Behold the yellow box in the address bar, missing text for tab names, and missing text in the reddit sidebar (read under "what does it do?" for easy to see examples). Also I just noticed in my example at least the letter "n" seems to be missing the most!

A quick recap of my personal experiences with this bug;

Happens much more often when a video is playing in a different tab or in my current tab.

Didn't happen in nightly but that was > 2 months ago.

Did happen with a new profile in current release firefox.

Does not happen when webrender is disabled.

(In reply to Jessie [:jbonisteel] plz needinfo from comment #35)

You mentioned that you see the issue with the black boxes about once a day. Have you noticed if there are particular websites where this seems to happen more frequently? Any common steps to reproduce you have found so far?

Would you be willing to try out Firefox Nightly for a week or so and let us know if it happens there: https://www.mozilla.org/en-CA/firefox/channel/desktop/ ?

I haven't noticed any websites causing it more often than others, it seems to happen at random. I've been using nightly for 2 days and so far I have not had this bug occur. I will keep using it for a few more days and report back if I see it happen again.

More black boxes and a UI glitch: https://www.reddit.com/r/firefox/comments/ewtvcd/does_this_happen_to_you/fgcmwub/

User confirms that disabling WR resolves the issue.

RTX 2070, Firefox 72 has been doing this for me, going to try turning off WebRender next.

Happens with WR enabled in Nightly on Fedora 31 + RTX 2070 and all recent Nvidia drivers up to and including 440.59. I use 2 monitors with my GPU and I'm using uMatrix, uBlock Origin, Request Control, The Dark Reader extensions and I have ui.systemUsesDarkTheme set to true if any of that matters. I have no clear STR at the moment, but now that I know this is being tracked, I'll take better notes.

This happens once every 1-2 weeks to me. Win10, GTX 1070. Been trying to find STR but it's just completely random. If anything, I think it might be triggered when I'm low on RAM but can't be 100% sure.

I can usually interact with the browser for a while and the bug continues to be present, so I could maybe capture some state during this? As in, some black boxes disappear on mouse move, but the situation doesn't resolve completely. In fact, if I don't restart the browser I find that it tends to crash shortly afterwards. I suppose one other thing I could do is link to a crash report occurring immediately after this bug.

I can reliably reproduce a glitch (see attached) on an Intel iGPU / Linux system when opening the browser and page menus for the first time. It starts working after mouse over. I'm not sure it's the same bug, as I get a white, not black background, but that might be related to the video drivers.

Possible STR for Fedora 31 + Nvidia RTX 2070 + v440.64 drivers:

1. login to your X session, launch Firefox normally, let all tabs load, browse around a bit, create some activity.
2. Ctrl-Alt-F2 into another tty and login
3. startx a full screen opengl game or application
4. exit the full screen opengl game or application and log out of this tty
5. Ctrl-Alt-F1 back to your main X session and get Firefox back into focus
6. Observe the black boxes and Firefox not really wanting to come back to life

Note: I'm using Firefox Nightly ASAN (Build ID 20200302094818). YMMV

Screenshot: https://imgur.com/bS2eg7k.png

(In reply to Asif Youssuff from comment #27)

Another report here:
https://www.reddit.com/r/firefox/comments/end5h5/
text_graphical_artefacts_appearing_randomly_in_ff/

User does not see the issue in Nightly.

This user reports that since upgrading to Firefox 74, they no longer see the issue.

Our suspected fix for some of these issues has shipped with 75. If there are still problems we can re-open.

bug 1617083