Browser issue JS error when posting (Flash uploader related)


Please: can someone check whether the service configuration is allowing browsers to cache content that should not be cached?

Tested beyond XenForo at MacRumors Forums:
  • the staleness of content from XenForo Community is evident with Firefox in safe mode.
Summary observations, from test results:

The frequent representations of stale content from XenForo here, and at MacRumors Forums, are reminiscent of frequent representations of stale content from Discourse.

For the Discourse cases, there's a recently committed fix.

(For posterity, I have MAFF and PDF versions of that test page.)


XenForo developer
Staff member
The fix mentioned in Discourse just outright disables caching of any page. The relevance here is that this blocks the back (and forward) buttons from using a cache, which is potentially rather detrimental to the browsing experience of anyone on a slow connection (or a slow server) and will likely increase server load. I don't think that's a great change.

From the linked thread, I'm not sure how the jump from the progress indicator to content caching was made. The example given with that indicator isn't a situation where caching would be involved.

The example given with that indicator isn't a situation where caching would be involved.

I did struggle to find a logical explanation for the problem. For the past ~three months I made the lazy assumption that an unusual combination of extensions was among the root causes of the problem. Plus a lazy assumption that my use of Firefox was a rarity (compared to use of Safari) in MacRumors Forums. I learnt try to habitually work around the problem by clicking 'More Options…' but often, I'm focused more on content than on workarounds so I instinctively click 'Post Reply'. The habit of using that button is surprisingly hard to break.

Finding the problem with Firefox in safe mode – with add-ons (including extensions) supposedly disabled – surprised me.

If you start Firefox in safe mode, do you reproduce the problem?
Last edited:


XenForo developer
Staff member
No, I can't reproduce that problem.

You likely need to open the browser console to see if there are any error messages shown there.


XenForo developer
Staff member
That very much looks like something broken within Firefox. That error would normally indicate a failure to communicate with some sort of external code such as Flash. The area that's triggering it though is just looking for HTML elements in the DOM.

One of those is somewhat tangentially related to Flash, but it's just an input. Regardless, try disabling the Flash uploader.
Perfect, thanks. is marked resolved, and renamed:
  • endless progress indicator when replying to a topic, worked around by disabling a feature of XenForo

I'll repeat below the test that I posted without difficulty, a few minutes ago, at


Thanks …

Side note: the greatest surprise to me (it may be common knowledge to some people) is that whilst Firefox does list Plugins under about:addons, those plugins are not disabled when Firefox reportedly disables all add-ons o_O

Adobe Flash Player enabled.png

– if Mozilla had been clearer about that contradiction in safe mode, we might have understood the problem sooner.

Back on topic …

Problems when replying inline

Yesterday's test at was successful.

Now, another test with:
  • Firefox 49.0 in normal mode on TrueOS Desktop
  • Electrolysis (e10s) enabled
  • Adblock Plus 2.8.2 and some other enabled extensions behaving as if they are not enabled (for at least some of these, the loss of functionality is to be expected whilst e10s is rolled out)
  • Adobe Flash Player (only slightly inferior to Adobe's current Extended Support Release (ESR))
  • XenForo's Flash-based uploader disabled
$ uname -v
FreeBSD 12.0-CURRENT #14 1717ae3(drm-next-4.7): Fri Oct 28 13:49:49 UTC 2016     root@gauntlet:/usr/obj/usr/src/sys/GENERIC
Thanks for the move! Apologies for the assumption of a bug.

… not sure how the jump from the progress indicator to content caching was made. …

My bad. Please change the subject line of this topic to whatever you think is most appropriate.

(There is an issue with stale content, but I need to investigate that at a later date.)

For the issue involving Adobe software: I'll perform some final tests, without FreeBSD, in the test area.

Thanks again