Hang and error?

[Herman Strange]

Have seen this a few times recently (Version 11.0.1-x64). There doesn't appear to be anything consistent about the cause, and usually happens when changing tabs or closing a tab. Thought I'd pass it on in case it was useful.

A script on this page may be busy, or it may have stopped responding. You can stop the script now, or you can continue to see if the script will complete.

Script: chrome://browser/content/tabbrowser.xml:1644

[Moonchild]

The script and location indicates it is waiting for the removal of tab arguments from the tab before closing it. This is most likely caused by an add-on.
It would help in this case if you could list your add-ons, and try to disable the ones that change tab behavior to see if that helps. It would also help if you have other script locations mention on your hang, to pinpoint the cause a bit better.

[Herman Strange]

I'll keep an eye out for other locations. My add-ons are:

Extensions:
Advertising Cooking Opt-out 1.5
Old Default Image Style 1.0
Shorten URL (Bit.ly) 0.70
Timestamp 1.4
Greasemonkey 0.9.18

Plugins:
Java(TM) Platform SE 6 U31 6.0.310.5
Shockwave Flash 11.2.202.233

User scripts:
Sweet Timeline 1.40

If it seems relevant at all, the browser usually goes into a "white windowshade" condition during the hang and then returns to normal appearance after clearing the message. If I then close the browser, it will ask me if I want to close "x" tabs when I only have "x-1" tabs open ... i.e. to close 3 tabs when I only have 2 open, etc.

[Moonchild]

Thanks for the listing. Can you at least try to restart with add-ons disabled and see if that fixes your issue? There are a few in there I'm not familiar with. Also check if they are listed as compatible with the current browser version - Mozilla has been making changes and tweaks to the Firefox user interface with each latest version, which might not play nice with older add-ons (or greasemonkey scripts, for that matter).

That you see x+1 tabs mentioned is correct if you stopped the script, because when you closed the tab, it was collapsed but not actually removed yet at the point where the script was stopped.

[Herman Strange]

Tried with Greasemonkey (and user scripts) disabled. Also checked for updates and compatibility of all addons and didn't find any issues there. Have been watching a bit more - the error message is consistent, but I still can't tell for sure where it's coming from - is it possible that it's being generated by script from the other end, i.e., Facebook or one of their advertisers? Better yet, is there any way I might be able to tell where it's coming from - error log or some such that FF/PM keeps?

<edit>Just saw that v12 has been released, will update now and see if anything changes - if it runs for a few days without the error I'll think it's fixed!</edit>

[Moonchild]

Tried with Greasemonkey (and user scripts) disabled. Also checked for updates and compatibility of all addons and didn't find any issues there.

...but you didn't try disabling all add-ons? You might want to try that, then enable them one by one until the error pops up again.

Have been watching a bit more - the error message is consistent, but I still can't tell for sure where it's coming from - is it possible that it's being generated by script from the other end, i.e., Facebook or one of their advertisers?

No, that's not possible. The script hangs on an internal chrome/UI operation, that can't be influenced by any script running in the content (would be a bad security hazard otherwise)

Better yet, is there any way I might be able to tell where it's coming from - error log or some such that FF/PM keeps?

You can check and see if the Web Developer -> Error Console provides any more clues. Pale Moon doesn't keep logs of UI operations, that would be too much of a performance drain.

[Herman Strange]

Following up - haven't seen the script error since upgrade to v12 - so appears to be gone. However, separate issue that I'll begin a new thread for.