I'm not sure how complete the list is, since Firefox Nightly is updated nearly daily, but you can see a list of previous Nightly releases on Mozilla's release archive server.

However, keep in mind that when you open Firefox Nightly, it's just going to download the latest version again. You would need to disable updates using Windows Group Policy or [[Customizing Firefox Using policies.json|a policies.json file].

That said, perhaps Firefox Nightly is not for you. It's not intended to be your regular browser anyway. It's really more of a testing browser. It can be very unstable at times because it contains features that are still under development. If you want to try the latest features, but want a more stable experience, perhaps Firefox Beta is the better choice.

Hope this helps.

The Nightly development channel is the most unstable as it gets two checkins so two updates each day. This can lead to issues until they are fixed, finished or reverted. This development channel is meant more for Devs and Testers and not regular Firefox users in mind. Do keep the Firefox (Nightly builds) install and Profiles separate from the Firefox Release and Nightly profiles used if you were to try.

Release < Beta (b#) < Nightly (a1)

The Builds threads in http://forums.mozillazine.org/viewforum.php?f=23 (a independent forum) can give you an idea of the checkins going in each day and current issues.

Thanks for the link, that's what I was looking for! I wonder why I didn't find the Nightly directory the last time I looked on that server.

Thanks for reminding me about copying the policies file. Good point.

Thanks for the advice, I'm sure it will apply to the majority of users who ask here.

Unfortunately the older build now refuses to run unless I create a new profile, which is not an option.

Using Nightly has been the only option for me as I see it. Mozilla seem to have decided that Firefox should give the impression of being slow or even reluctant to integrate with the platform it runs on. Either that or they've been dragging their feet for 10 years before even starting to implement features considered standard on the platform they've chosen to release for, like pinch-to-zoom. Even after a decade the feature is still so broken in Nightly that the competition was significantly better at it 5 years ago. Not to mention every other missing integration, like system text utilities like replacements and spell checker, access to system services in context menus, system picture-in-picture support, etc. I can't imagine that going from Nightly to Beta could possibly be anything other than going from bad to worse in this regard, and I just don't have the energy to keep reading bug reports to determine whether fixes for the latest features (from ten years ago) are present in the Beta channel as well.

Even using Nightly for the remote chance of receiving an update that doesn't use 5x the energy of other browsers, and thus making Firefox an option when on battery power, would be worth it.

Nightly is a tiny sliver of hope for the features I would otherwise be waiting, who knows, another ten years for. To me it's basically Nightly or no Firefox at all. To even be able to use it properly I have to edit config files just for the privilege to not be nagged about updates every five minutes, and I've just now realized that it wants to take away my decision of which version to use in the backward direction as well. If someone who is babysitting their browser to this extent can't simply downgrade without having the application intentionally throw roadblocks in the way then I think that's my cue to reevaluate the alternatives.

And that's why Nightly is (was) for me.

I wanted to see it succeed, so it's a bit sad to have to admit to myself that what I currently believe in most about Firefox is its market share. This forum has always been helpful though, thanks.

onetimename said

Unfortunately the older build now refuses to run unless I create a new profile, which is not an option.

In Firefox 67, the developers introduced downgrade protection. It's there to prevent you from running your profile in an older version of Firefox. Depending on what changes are made between versions, some of the files in your profile may be changed and may not longer work on older versions of Firefox.

However, you can bypass downgrade protection by using the -allow-downgrade command line option, if you ever wanted to change back to something other than Firefox Nightly (Release, ESR, Beta, etc).

Of course, I always recommend that you back up your local Firefox profile folder BEFORE attempting to start an older Firefox with downgrade protection. That way, if there is a change that prevents you from downgrading successfully, you will still have a copy of your original data.

You should never downgrade a nightly profile to beta or release because Nightly builds have a lot of features enabled that aren't ready for release (e.g. XULStore uses RKV storage and not xulstore.json) and you run a high risk that your data gets corrupted.

• https://wiki.mozilla.org/Storage

However, you can bypass downgrade protection by using the -allow-downgrade command line option, if you ever wanted to change back to something other than Firefox Nightly (Release, ESR, Beta, etc).

Thanks, that worked. It was necessary in order to downgrade Nightly to last week's build.