Fenix: [Enhancement] create an informative page for about:config that explains why it doesn't work in the stable release

[Pomax]

~This can't _possibly_ be intentional, especially given that customized settings are basically nonexistent at the moment.~

We've spent a long time marketing Firefox as the browser that puts you in full control, which means users expect about:config to work. Even if we have good reasons not to expose it in the main release (I disagree, it does not reflect well on us to force users into either having "no control", or having "control, but your browser may be broken"), we should make sure that when users do try to go to about:config they don't get an opaque network error that suggests we have a bug that's affecting one of the most important features of Firefox they're familiar with.

Instead, they should get an informative page that explains why, for Android, the about:config location doesn't work, that this is intentional, and what they can do if they really need it back in their life. Seeing the following is not good enough a treatment of folks who care enough to use our browser instead of Google's built-in product:

[s-ankur]

Duplicate of https://github.com/mozilla-mobile/fenix/issues/7865.

About config is available in nightly as well as beta versions for now. Also note that due to some technical reasons about config is no longer used to alter UI related customisation, just internal behaviour in fenix. Please read that issue for more information

[Pomax]

Then please consider this a signal that the about:config page load in regular FF for Android should say what you just said. It shouldn't be a network error, but a page that goes "Hi there, poweruser! We changed how about:config works (see [link] for more information), so if you want to keep using it, try out Firefox Nightly! Please visit [playstore link] if you want the maximum amount of control _and_ help out Firefox for Android by using future versions before anyone else!" or something similar.

[s-ankur]

Yes, the error page does seem pretty uninformative.

[dglttr]

the about:config page load in regular FF for Android should say what you just said

This is a great idea, giving more transparency.
Suggestion: Change the title of this issue and the description in the first comment so that this issue can be properly triaged and tracked. Maybe, they can implement this soon!

[Pomax]

@liuche did this land? If so, is there a crosslink for the PR? If not, then there isn't really a reason to close this.

[liuche]

Dupe of #7865

[Pomax]

No, it isn't. This issue has been morphed to acknowledge that about:config doesn't exist except in Nightly, and that there is work left to do to make sure that this is clear to our users.

The comment thread made that pretty obvious, and the issue title had already been updated, but the first comment had not. That's been fixed, please reopen this issue.