1263278 - [e10s] Multi-process cannot be enabled in about:preferences

Status: RESOLVED INCOMPLETE

(Firefox :: Settings UI, defect)

Description

[Josh Tumath]

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:48.0) Gecko/20100101 Firefox/48.0
Build ID: 20160408030212

Steps to reproduce:

Using a Windows 10 64-bit PC with 64-bit Nightly installed. Not using a touch screen monitor.

The bug started after a Nightly update a couple of days ago. I suddenly noticed that e10s is disabled (however, this bug happens in Firefox Dev Edition as well).


Actual results:

The option to enable e10s in about:preferences was disabled.

I noticed that, in about:config, I have three preferences:
browser.tabs.remote.autostart: true (user-set value)
browser.tabs.remote.autostart.1: false (default value)
browser.tabs.remote.autostart.2: false (user-set value)

If I try to set all these values to false, every time I restart Nightly, browser.tabs.remote.autostart keeps setting itself to true.

Comment 1

[David Clark]

Have you tried going to about:support and seeing what it says under Multiprocess Windows? If it says disabled by accessibility features (which I had) you just need to reset the modified accessibility preferences in about:config then restart and the option should be able to be enabled again.

Comment 2

[Josh Tumath]

(In reply to David Clark from comment #1)
> Have you tried going to about:support and seeing what it says under
> Multiprocess Windows? If it says disabled by accessibility features (which I
> had) you just need to reset the modified accessibility preferences in
> about:config then restart and the option should be able to be enabled again.

There was no message next to the check box reporting that the reason why it was disabled was because of the accessibility support. But as I say in comment 0, I reset the prefs, but they just kept changing back again. But I wouldn't be surprised if the accessibility feature was the cause of it being disabled, even if that message didn't appear. I just assumed it wasn't caused by that because the message wasn't there.

(I have fixed it now by refreshing Firefox, but have kept the old profile for this bug report.)

Comment 3

[:Gijs (he/him)]

The prefs here have changed a lot since this bug was filed, as has our ability to deal with a11y in e10s, so I'm going to close this out. If you're still having issues with Firefox not using e10s, please file a new bug with up-to-date steps. I don't think we'll add toggles to turn e10s off to our UI preferences because it leads to a strictly worse (and less well-tested) user experience at this point in time.