Phasing Out the Older Version of Firefox Sidebar in 2026

[asafko]

Hi folks, 

Over a year ago, we introduced an updated version of the sidebar that offers easy access to multiple tools – bookmarks, history, tabs from other devices, and a selection of chatbots – all in one place. As the new version has gained popularity and we plan our future work, we have made a decision to retire the older version in 2026. 

Old sidebar version

Updated sidebar version

I know that changes like this can be disruptive – especially when they affect established workflows you rely on every day. While use of the older version has been declining, it remains a familiar and convenient tool for many – especially long-time Firefox users who have built workflows around it. 

Unfortunately, supporting two versions means dividing the time and attention of a very small team. By focusing on a single updated version, we can fix issues across the Firefox frontend more quickly, incorporate feedback more efficiently, and deliver new features more consistently for everyone. For these reasons, in 2026, we will focus on improving the updated sidebar to provide many of the conveniences of the older version, then transition everyone to the updated version.

Here’s what to expect:

• Starting with the late Firefox Nightly 148, we have turned on the new sidebar by default for Nightly users. The new default will remain Nightly-only for a few releases to allow us to implement planned improvements, existing community requests, and collect additional feedback.  
• In Q2 2026, all users of the older version in release will be migrated to the updated sidebar. After the switch, for a period of time, we will keep the option to return to the older version to support folks who may be affected by bugs we fail to discover during Nightly testing. During this period, you will still be able to temporarily switch back to the old sidebar by going to Firefox Settings > General > Browser Layout and unchecking the Show sidebar option. 
• In Q3 2026, we will fully retire the original sidebar and remove the associated pref as we complete the transition.

Our goal is to make our transition plans transparent and implement suggested improvements that are feasible within the new interaction model, while preserving the speed and flexibility that long-time sidebar users value. Several implemented and planned improvements to the updated sidebar were informed by your feedback, and we expect that to continue throughout the transition: 

• Hide sidebar launcher on panel close if it was hidden prior to panel open (planned)

• Full screen mode doesn’t hide sidebar tools (planned)

If you’d like to share what functionality you’ve been missing in the new sidebar and what challenges you’ve experienced when you tried to adopt it, please share your thoughts here or file a bug in Bugzilla’s Sidebar component, so your feedback can continue shaping Firefox. And if you have a chance, please consider peeking at the existing metabug to see what improvements are already on our radar. 

[Kvin]

Hello, I believe this is the correct decision.

Could you also abandon the old profile system or combine the old and new profile systems?

And abandon the Firefox Focus/Klar browser?

Will there be further improvements to the sidebar, such as:

Auto-hide and auto-open the sidebar on hover when vertical tabs are not in use, for example, when history or bookmarks are expanded?

Vertical and horizontal tabs enabled simultaneously?

Support for all sidebar extensions, as well as support for widgets and opening websites in the sidebar?

So that the highlighted sidebar icon button is not displayed, because it is distracting.

Thank you!

[s_hentzschel]

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@Kvin wrote:

And abandon the Firefox Focus/Klar browser?

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What advantage do you gain if other users can no longer use what they like to use? 🤔

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@Kvin wrote:

Support for all sidebar extensions, as well as support for widgets and opening websites in the sidebar?

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Which extension do you think is not supported?

Regarding opening websites in the sidebar, they are working on a split tab feature. If you make one window narrower than the other, it's basically a sidebar.

[bty23]

Please don't abandon firefox focus. 

[toe_head2001]

In the old Sidebar version, it was possible to select multiple History items, and delete them all at once with the Delete key. This functionality seems to be missing from the new Sidebar version.

[sclem]

We have a few bugs about deleting history items that's part of the planned work, specifically deleting with the delete key and multiselecting items to delete them. 

[VulgarAscetic]

This is great to hear, thanks!

It would also be really useful to increase the width of this scrollbar in the sidebar. It's currently tiny on 1440p resolution and really hard to grab.

It also auto-disppears after a second which is really awkward and I need to keep moving my mouse to keep it visible, which adds to the difficulty of actually clicking on it.

[VulgarAscetic]

Seconding the issue mentioned above regarding deleting History. The new sidebar makes it extremely awkward and cumbersome to delete multiple history items.

[geofflawrence]

Does this mean that https://addons.mozilla.org/en-US/firefox/addon/side-view/ will stop working? I hope not, because I really do like it! Of course building Side View into Firefox would be fine by me.....

[sclem]

Nope! Extensions that previously worked in the old sidebar continue to do so in the new sidebar. And if you are a sidebery or tree style tab user and don't want to see any tabstrips, that is an option too (Click on "vertical tabs" then "hide tabs and sidebar" in the customize sidebar panel (click the gear icon) but I think you'd only be able to open an extension panel from there by using a keyboard shortcut and if you hit the sidebar button is will expand the launcher with vertical tabs).

[geofflawrence]

Great! Thanks for letting me know. I use it as a temporary view on a link, so how it is right now, works perfectly for me.

[morello]

I want to close the sidebar and have it automatically appear when the mouse moves to the side. Currently, these two options cannot be enabled simultaneously.

[s_hentzschel]

I really like the new sidebar design and it makes perfect sense not to keep two implementations for the same thing permanently. There is only one thing that is very annoying for me and it's the only reason why I disabled the new sidebar. It's great to see that there are already plans to address this:

@asafko wrote:

• Hide sidebar launcher on panel close if it was hidden prior to panel open (planned)

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[asafko]

Hi! Wanted to post a quick update here and note that this behavior has been implemented and will ship in Firefox 151, on May 19th. 

[s_hentzschel]

Thanks! It's much better now. 🙂

[johnrobert1234]

In the old Sidebar, you could select multiple history items and delete them together using the Delete key, but this option is no longer available in the new Sidebar.

Regards: ff beta testing

[sclem]

Hi, please see my response to someone else's comment about this: https://connect.mozilla.org/t5/discussions/phasing-out-the-older-version-of-firefox-sidebar-in-2026/.... We have worked planned for that.

[lackey]

That's a link to malware

[TechHorse]

I have given the new history sidebar another try, and it's good to see that a lot of the issues I had previously have now been fixed. There are still some, however, especially for us keyboard users. I will list some below.

(Sorry if these are already known.)

----
Unlike the current history side panel, the new side panel doesn't remember the last sort order used. Every time I re-opened it it had reverted back to "Date". I only use "Last visited", so obviously I do not want to have to start manually opening the sort menu and re-selecting this each time.

----
The search function is broken in "Last visited" view. No results are found for any search term.

----
While search appears to work correctly when sorting by "Date", the long-standing (and documented) method of listing all history items by entering a space into the search box does not work. I suspect that it is instead returning a literal search for anything that contains a space?

----
In "Date" view, using tab and shift+tab to move between elements can be flaky and will stop working under certain circumstances. They work correctly if either the "Today" header or the URLs within the "Today" list are selected. However problems start once you move to older date subgroups.

For example:
Press ctrl+H to open the history side panel.
Press tab until the "Today" date header is selected.
Press left to collapse the "Today" list.
Press down to reach the next date header.
Pressing tab / shift+tab now has no effect.
Press down to access the expanded URLS under this older section.
Both now work, however shift+tab will take you back to the date group header, and from there again both stop working. This affects, for example, getting from the history list back to the search box.

[Afxs]

Supprimez cette barre latérale dans une option ! Elle reste affichée en blanc quand on a un écran en fond noir pour les yeux. Je ne l'avais jamais eue, et voici que depuis quelques jours, elle est apparue. Merci de ne l'activé que pour ceux qui la veulent.

[tigerbalm]

The new sidebar is about 100px bigger than the old one - this is significant, and this space on the left is mostly empty. I wish you could collapse it entirely to leave just the selected view, like in the old version.

[s_hentzschel]

You can drag the width to any value you want. Even with the new sidebar launcher and the minimum width of the sidebar, it's only 50px difference and not 100px.

[tigerbalm]

Here's an example. The width of the "all tabs helper" view is the same as before. But the new sidebar adds 88 pixels of extra space, which is closer to 100 than 50. This area also cannot be shrunk - you can only change the selected view's width, but not the side margins.

[Anonymous]

Yes. The new sidebar is very bad design. 
Too much padding. 

Mozilla leadership is dismal. 

[TechHorse]

Hello. I Triwd the new sidebar again in Firefox 148.0.2 and have some more feedback on the issues that I am having as a keyboard user. The following relate to lost functionality or more difficult usage, in comparison with the original.

I did visit the Bugzilla meta thread linked in the first post and will try to avoid mentioning anything that is already known, but apologies if I missed some reports and end up describing already filed issues.

Lastly for this preamble, the following relates to the history sidebar with the "Last visited" view. I did not test other sidebars or views.

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Unfortunately there has been a major regression since the version I tested in February.

Once again it seems that each individual entry in the site list has been given its own position in the F6 and tab cycles.

This does not happen with the old sidebar, and in the following post under the first "----" section I originally described why this posed a major navigational issue. Both for the sidebar and the Firefox UI as a whole.
https://connect.mozilla.org/t5/discussions/sidebar-and-vertical-tabs-release-channel-experimentation...

Last month I was pleased to see that this had now been fixed and that the F6 and tab cycles were working similar to how they did originally. But now the issue is back.

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I have seen that the lack of some standard OS keyboard multi-select techniques has already been raised. Such as ctrl+a to select all items and shift+arrows to select some consecutive items.

But also missing is the ability to select several non-consecutive items by holding down the ctrl key while arrowing and pressing space to select / deselect individual list elements.

I'll give a real-life usage example of this technique that I use regularly with the old sidebar.

Let's say that yesterday I read a number of Mozilla Connect threads and today I want to catch up with a few of them.

I type "Connect" into the search field and it turns out that I want to open result #3, #5 and #9.

I arrow down to #3, at which point this is the only selected item. I then hold down the ctrl key and arrow down until #5 and press space, then arrow down until #9 and press space, before finally releasing the ctrl key.

At this point only #3, #5 and #9 are selected, and I can then open the context menu and select "Open All in Tabs".

(Or delete them, or copy their URLs to the clipboard, or perform any other bulk operation I wish to on just those three.)

However, with the new sidebar ctrl+space now immediately opens the site in a new tab, and switches keyboard focus to it. Making the multi-selection of non-consecutive items in the sidebar impossible.

----
I've just mentioned the loss of ctrl+space as an item selector, in favour of it becoming a functional duplicate of ctrl+enter.

Similar has also happened to space. It is now equivalent to pressing enter. That is, it loads the site straightaway, rather than simply selecting it if it was currently unselected.

The change to the behaviours of both space and ctrl+space make me nervous, as for years I have been pressing space to select a single item if it was not already selected, or ctrl+space when selecting multiple sites.

This means that I might end up unintentionally visiting a site that I was actually intending to delete or even "Forget About This Site", for example.

----
Another technique for opening several non-consecutively listed sites has also become more work.

With the old sidebar pressing ctrl+enter would open a site in a new tab but would not switch to it, and the keyboard focus would stay within the site list.

This means that you could open several items relatively quickly by arrowing and ctrl+entering one after another. You can then close the sidebar and read each site in turn.

But in the new sidebar ctrl+enter performs the same action that ctrl+space now does. As described previously, this switches tab straight away and moves focus to the website, meaning that you will have to F6 and tab etc. to get back into the sidebar list.

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If you are in the search field of the old sidebar then a tab press moves to the view menu button, then another moves to the sites list.

With the new sidebar pressing tab on the view menu button causes the keyboard to enter into some sort of freescroll mode, where the arrow keys scroll the list of sites visually but without changing the keyboard focus. You need to tab again to move the focus into the list to start selecting an item.

Is this a bug or intentional? If intentional then I am not sure that I understand the rationale?

I can understand why a mouse user would mouse scroll through a list, as if they find what they want several page scrolls down then they can just click on it.

Whereas with this keyboard freescroll if the user sees what they want 100 items down the list, well they will still need to then press tab to get the focus into the list, then arrow or pagedown from the start to #100. So they might as well have been arrowing or pagedowning through the elements in the first place, that way when they do find what they are looking for the keyboard focus is already close to it?

So yes, not sure why this extra element is there, and it means that the user has to press tab three times to get from the search field to the results, whereas the old sidebar required just two presses.

[Jicetus]

The sidebar is a massive leap forward, especially used together with the split-view functionality:)

However, for users with multi-monitor setups (e.g., one landscape and one portrait), the global sidebar setting can be limiting. Would it be possible to explore any of these?

• Per-window sidebar toggling (enable/disable independently per window)?
• A "main window" mode (sidebar only appears in one designated window)?
• Conditional display (e.g., sidebar only appears if window width exceeds a set threshold)?

Would help optimize screen real-estate, especially for users with constrained monitor widths. If this won't be coming down the pipeline, is there a workaround that could achieve similar functionality?

I originally posted this here, in the Sidebar and Vertical Tabs Launch in Release 136 discussion/announcement thread. But since that thread is quite a bit older and for an earlier version, I wasn't sure if it was still being read.

[sclem]

Hi! Thanks for resurfacing this request. This sounds like something that'd be useful for many users so I've filed a bug to keep track of the request, which you can follow. https://bugzilla.mozilla.org/show_bug.cgi?id=2028447

One question though, do you use vertical tabs and if so do any of the various settings help with the screen real estate issue, ie (the "Expand sidebar on hover setting" will keep the sidebar collapsed until you hoover on a tab)? It'd help to know what your default set up is.

[mamta25]

Thanks for the update. I get why you’re moving to just one sidebar version. It’s good that there will be a proper transition period so users can get used to it. Looking forward to seeing the improvements in the new sidebar.

[cris123]

Salve avevo  gia postato ma  il mio post e sparito quindi lo risegnalo grazie: Ecco il testo completo e dettagliato per la tua segnalazione, integrato con tutte le specifiche che mi hai indicato. Ho descritto esattamente il passaggio dal comportamento corretto precedente alla rottura attuale, sottolineando che il problema è nato con l'aggiornamento.

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## Segnalazione Bug: Regressione totale interfaccia Firefox con Contrasto Elevato di Windows 11

**Descrizione del problema:**
A seguito dell'ultimo aggiornamento, il sistema di rendering di Firefox è stato compromesso per chi utilizza la modalità **Contrasto Elevato** di Windows 11. Il browser non riesce più a mantenere la coerenza visiva, ereditando in modo errato i colori dal sistema operativo e rendendo l'interfaccia inutilizzabile.

**Comportamento precedente (Corretto):**
Prima dell'aggiornamento, l'esperienza era ottimale e funzionale:
* Selezionando il tema scuro, tutto lo sfondo dell'interfaccia (barre laterali, barra superiore e schede) risultava **completamente nero**.
* I testi e le icone erano **bianchi**, garantendo un contrasto pulito, leggibile e senza distorsioni grafiche.
* Il browser rispettava la scelta dell'utente, integrandosi perfettamente con la modalità di accessibilità richiesta.

**Situazione attuale dopo l'aggiornamento (Errore):**
L'ultimo aggiornamento ha "rovinato" il sistema. Ora Firefox eredita forzatamente i colori del "Contrasto Elevato" del sistema operativo, ma lo fa in modo errato:
* **Bordi Gialli Invasivi:** Come visibile nell'immagine, sono apparsi bordi gialli spessi attorno alla barra degli indirizzi, ai pulsanti e alla cornice della finestra.
* **Barre Laterali Alterate:** Le barre laterali (comprese quelle dei servizi come WhatsApp/Facebook) non sono più nere con scritte bianche, ma hanno assunto un colore grigio/celeste che annulla il contrasto e rende le icone e le scritte confuse.
* **Incoerenza delle Schede:** Le schede in alto hanno perso la loro definizione originale, assumendo i colori del tema di sistema che ne rendono difficile la distinzione e la lettura.

**Prove concrete effettuate:**
* **Modifica del Tema di Sistema:** Ho effettuato tutte le prove possibili modificando il tema a contrasto elevato di Windows 11 in diverse combinazioni, ma non c'è modo di far tornare Firefox al comportamento precedente. Il browser ignora le modifiche e mantiene questa visualizzazione errata.
* **Confronto con Tema Scuro Standard:** Se disattivo il contrasto elevato e uso il normale tema scuro di Windows, Firefox non presenta problemi. Tuttavia, la modalità contrasto elevato è per me necessaria e il fatto che l'aggiornamento ne abbia rotto la compatibilità è un grave problema di accessibilità.

**Conclusione:**
È evidente che l'aggiornamento ha modificato il modo in cui Firefox riceve i colori dal sistema operativo, forzando un'interfaccia che prima era nera e pulita in una configurazione frammentata e illeggibile. Chiedo che venga ripristinato il supporto corretto che permetta di avere nuovamente lo sfondo nero e le scritte bianche anche in modalità contrasto elevato.

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[cris123]

mancava foto