Pale Moon 34.3.0 crashing when minimized

ajgelado · Post by **ajgelado** » 2026-06-06, 05:22

I started getting random crashes after the upgrade to v34.3.0 a few days ago. The pattern is startling, to say the less. They don't happen when Pale Moon is in active use, nor when under memory pressure. What happens is that, after browsing for some time, I close the window I have been working on, I minimize the window with my default set of tabs, and then, a few seconds, perhaps a minute later, PM closes itself. Silently. No error message, no action from my part. It just disappears from the task bar and the process is gone. The default set of tabs are static pages, mainly home grown web apps, neither of which show any ads or do anything strange/suspicious, so I doubt they are to blame - and I have had no problem with them for months/years.

I don't think they are caused by an add-on, either, because AFAIK the ones I use haven't been updated recently (most of them are quite old and saw the last update years ago). And, again, they didn't seem to cause any problem before v34.3.0.

The crashes happen usually when I have been using Pale Moon for some time without rebooting, but memory usage by PM rarely exceeds 1-2 GB (and, for the record, I'm using the 64 bit build on a 16 GB system, so there should be plenty of room). Maybe it is related to garbage recollection, triggered by the window being closed? A hint in that direction is that, after closing a memory intensive tab, sometimes PM is sluggish for some time (seconds to tens of seconds) before returning to its being. Maybe it's a reverse placebo effect, but I don't remember that effect being so sever before v34.3.0.

Given the nature of the crashes (intermittent, silent, after some time of use), I don't know what can I do to diagnose them or provide more information. Maybe I could somehow enable post-mortem dumps?

Post by **andyprough** » 2026-06-06, 05:44

ajgelado wrote: ↑
2026-06-06, 05:22
I started getting random crashes after the upgrade to v34.3.0 a few days ago. The pattern is startling, to say the less. They don't happen when Pale Moon is in active use, nor when under memory pressure. What happens is that, after browsing for some time, I close the window I have been working on, I minimize the window with my default set of tabs, and then, a few seconds, perhaps a minute later, PM closes itself. Silently. No error message, no action from my part. It just disappears from the task bar and the process is gone.

This is interesting, we'll make this a separate thread as your experience may be different from @UCyborg's. Please post the output of Help - Troubleshooting Information in code tags so that we can start trying to diagnose this. Also, you may want to list some of the sites that are open in tabs when Pale Moon crashes for you.

Post by **Moonchild** » 2026-06-06, 10:46

Of note, we are aware of "idle" crashes being caused on some sites (most notably GMail) due to an issue with the newly-introduced FinalizationRegistry API. It unfortunately serves as a demonstration why the whole WeakRef spec is dangerous as it can cause problems at unexpected times when garbage collection runs (also in the background).

Post by **RealityRipple** » 2026-06-06, 17:34

Left my browser open minimized all night last night; still running on the same instance right now. Time to narrow down extensions and pages.

KlarkKentThe3rd · Post by **KlarkKentThe3rd** » 2026-06-06, 19:00

Read this thread, got inspired, minimized a window for 2 seconds, the un-minimized it. Went for a leak, came back to a crashed PM. Almost lost my session too (but jumped through 4 hoops and got the missing tabs back).

Sessh · Post by **Sessh** » 2026-06-06, 20:20

I was just going to make a report about this. PM keeps crashing while minimized, but it takes hours for it to happen. It's not related to any specific website that I can see. I've had it crash overnight (this PC is on 24/7 and PM is usually open 24/7 without issues) and sometimes it won't, it crashed once on a DDG search page, sometimes it'll crash just being idle, but always minimized. It doesn't seem to be related to using a lot of memory. This didn't happen before the latest update. When I reopen it, it opens in a small, square window instead of opening maximized like usual. Don't know if that gives any clues.

To the OP's comments about garbage collection, this does seem to have gotten worse. I find myself having to restart the browser more to get rid of the brief freezes every few seconds. Amazon seems to do this more now and is more of a pain to use.

Post by **Moonchild** » 2026-06-07, 11:26

I'm going to see if I can re-introduce the pref to disable WeakRef plumbing while leaving the content-facing APIs. I've done some more reading into the spec and there's actually a strong argument here that a stub implementation that doesn't actually do anything with the garbage collector is fine. That should avoid these crashes (and neuter a dangerous API).

Most notably:

WeakRefs' .deref() does not guarantee garbage collection happens soon or at all. So we shouldn't have to do anything beyond giving JS the API side.
Finalizationregistry's callback mechanism is completely optional, per spec:
A conforming JavaScript implementation, even one that does garbage collection, is not required to call cleanup callbacks.

So neither WeakRef.deref() nor FinalizationRegistry callbacks are required to do anything and could just be no-ops. There are even clear and present warnings on MDN about not relying on the JS engine to honor these features.

tooshorttoolong · Post by **tooshorttoolong** » 2026-06-07, 21:46

Just chiming in to mention that I’ve also had numerous "idle" crashes of Pale Moon since the update to 34.3.0 (on Linux).
I don’t minimize it, but I do use several virtual desktops and PM usually crashes while I’m on another desktop.

I think in my case this page might be triggering it: https://codepen.io/volv/full/bpwRLL/ (might need a click on "Calculate", not sure). I had PM running fine for several hours today until I opened this page, then some time later, it crashed.

Edit: BTW…

KlarkKentThe3rd wrote: ↑
2026-06-06, 19:00
Almost lost my session too (but jumped through 4 hoops and got the missing tabs back).

I recommend the Session Manager addon!

ajgelado · Post by **ajgelado** » 2026-06-08, 03:57

andyprough wrote: ↑
2026-06-06, 05:44
This is interesting, we'll make this a separate thread as your experience may be different from @UCyborg's. Please post the output of Help - Troubleshooting Information in code tags so that we can start trying to diagnose this. Also, you may want to list some of the sites that are open in tabs when Pale Moon crashes for you.

Bellow is the text from Help->Troubleshoot:

The tabs open when the crashes happen aren't interesting in themselves, as they are sites I have been visiting for some time (in the case of MDSN, *decades*) without problem. They are:

MSDN (https://msdn.duke4.net/hot.php), aka Mikko Sandt's Duke Nukem, a website about Duke Nukem 3D
Hardcore Software (https://hardcoresoftware.learningbyship ... f-contents), powered by Substack
A couple of private web apps, hosted locally and based on a home grown PHP framework/ORM/CMS.

MSDN uses no Javascript at all (its design hasn't changed since the late 90s!), and my web apps use Javascript only for the popup menus. Substack (and thus Hardcore Software) is the only page which uses Javascript. Load is a bit slow, but once loaded, CPU use falls to zero.

Anyway, reading other posters' experiences, this seems to be caused by the sites recently closed. Oddly, Gmail and YouTube have not caused trouble for me, but I don't use them too much in Pale Moon: I have Firefox (gasp!) installed just to access Google apps. Next time it happens, I'll try to make a list of recently closed tabs/windows.

Post by **Moonchild** » 2026-06-08, 05:27

We're working on it. I think I found the fix for these crashes.

KlarkKentThe3rd · Post by **KlarkKentThe3rd** » 2026-06-08, 09:33

tooshorttoolong wrote: ↑
2026-06-07, 21:46
I recommend the Session Manager addon!

It's 6 years old and does not seem to support PM34.

therube · Post by **therube** » 2026-06-08, 18:51

This, Session Manager ?
Six years, yes, but did install, & seems to be working here, 34.3.0.

(Now, I didn't give it a full run through, but set it to prompt on browser open, which it did, & I selected the last session, which worked.)

Sessh · Post by **Sessh** » 2026-06-10, 20:26

Just so people in this thread affected by this know, 34.3.0.1 is out to hopefully address this issue, so grab it if you haven't yet. We shall see.

ajgelado · Post by **ajgelado** » 2026-06-10, 22:55

I already have it installed in my two work machines. So far I have had no trouble; but as the problem tends to manifest itself after hours of use, more testing will be needed. I will get back with my experiences.

Sessh · Post by **Sessh** » 2026-06-11, 20:00

Well, mine didn't crash overnight and hasn't crashed yet today, so seems fixed? If it crashes again, will report here.

Post by **Moonchild** » 2026-06-11, 20:03

This particular issue should be fixed. If you're interested in following the technical process you can have a look through Issue #3111 (UXP).

Lucio Chiappetti · Post by **Lucio Chiappetti** » 2026-06-11, 20:56

I had sporadic silent crashes, but now I am on 34.3.0.1 (Linux) and none occurred since the upgrade.

Instead today I was at a disabled friend's who uses PM on Windows. I had to do an operation for him which requires the use of a smart card reader with the national electronic identity card. For some reason the operation failed (I logged in to the card, but when the site required OK to the certificate it kept asking, then entered the site and "something is gone wrong". I suspect that an automatic upgrade to 34.3.0.1 was in progress during the authentication, and was not completed when I exited Pale Moon. Maybe it had not yet loaded the language pack. After the upgrade was completed with a restart, we had no further problems.
(I have configured automatic upgrade for him - I use upgrade-on-request instead ... sometimes I actually upgrade before being requested; anyhow all is well what ends well)

ajgelado · Post by **ajgelado** » 2026-06-13, 03:18

I can confirm that in the two days since I upgraded to 34.3.0.1 I haven't had a single crash, whereas 34.3.0 crashed once or twice a day. From what I see, the issue is solved.

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