Firefox 40 blank with no menu

[Louis Ferranti]

Please do not ignore this bug report because it has not been submitted via Apport. Due to the severe issue with Firefox 40 I cannot currently complete the Apport submission process so am having to report this manually.
Firefox was upgraded from 39.0.3+build2-0ubuntu0.12.04.1 to 40.0+build4-0ubuntu0.12.04.1 yesterday evening (15/08/2015) and now when it runs the entire window is grey with no content and there is no menu. The computer is running Xubuntu 12.04
Trying to run Firefox in safe mode results in a small window titled Firefox Safe Mode which contains just grey.
When it is used to open help in the Xubuntu applications menu (no help displayed, only blank grey window) and the top right X window close symbol is clicked the 'Confirm close' window appears but it too is grey and has no content and I can only terminate the application using Task Manager. The same happens when I run Apport when it reaches the stage where Firefox is invoked. This may not be relevant but tcpdump shows when it was first opened Firefox 40 did communicate to ec2-54-200-163-149.us-west-2.compute.amazonaws.com so it is capable of connections. Disabling the Firefox Apparmor profile does not make any difference. I will try to provide any further information requested as best I can. If I can provide the requested information via e-mail that would be preferable as Firefox is not operational and if the previous version is reverted to it will not exhibit the bug.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Eddy De Greef (edg-pub)]

I see exactly the same problem on Linux Mint 17.
Maybe relevant: I'm running the 32-bit i386 version (old Pentium PC).

[Louis Ferranti (louis-ferranti)]

Using sysinfo I can see the computer this is occurring is also a 32 bit Intel Pentium 4 CPU machine (family 15 model 2 stepping 9). It may be old but using Xubuntu means it can do everything necessary (and more) that a modern Windows machine does as fast, other than booting. Here is some additional information :
Kernel - 3.2.0-88-generic (#126-Ubuntu SMP)
GCC version is 4.6 (i686-linux-gnu)
Xorg version is 1.11.3
Graphics are via Intel 82845G/GL(Brookdale-G)/GE Chipset integrated graphics device (rev 01) with a Intel 5247 subsystem

[Louis Ferranti (louis-ferranti)]

I have attached a copy of the /home/this-user/.mozilla/firefox/console.log which may help the relevant developers identify why the console is inoperative. It contains details of console error conditions which seem to have only commenced after the update to 40.

[Louis Ferranti (louis-ferranti)]

A solution to this has been found thanks to https://support.mozilla.org/en-US/questions/1077299. If the .mozilla/firefox/******.default/prefs.js entry for gfx.xrender.enabled is manually changed from false to true the window displays with content and menus. Hopefully this will be useful to others encountering the issue and may thanks to those who found the solution.

[Paul White (paulw2u)]

Further to comment #5 by the reporter the issue was fixed by a configuration change.