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If Firefox’s Nova interface changed the buttons or layout you prefer, recent Mozilla Support forum replies report a possible workaround: open about:config, set browser.nova.enabled to false if that preference exists, then restart Firefox if needed. This is a community-reported, build-dependent setting—not an officially documented Mozilla control or a guaranteed permanent way to restore the classic interface.
How to turn off Nova in Firefox
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Enter
about:configin Firefox’s address bar and press Enter. If Firefox displays a warning, proceed to the Configuration Editor.# Preview Product Price 1 
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Search for
browser.nova.enabled. -
If the preference appears, change its value from
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Check whether the interface changed. If not, restart Firefox and check again.
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These steps reflect community support answers posted September 29–October 1, 2026, including reports referring to Firefox 157. Mozilla’s official documentation reviewed here does not confirm this Nova preference. The reports do not establish compatibility across Firefox versions, release channels, operating systems, or managed installations, and Mozilla has not documented that the setting will remain available. The relevant Mozilla Support discussion is the basis for treating this as a possible workaround rather than a guaranteed setting.
What to do if the setting is missing or has no effect
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If
browser.nova.enableddoes not appear, do not substitute another preference just because its name contains “nova.” The reviewed official material does not validate other Nova-related preferences as a way to restore the old interface. -
If the preference is present but changing it does not help, it may not control the interface in your particular build. The available evidence does not establish a universal fix or a permanent official classic-UI switch.
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If Firefox is managed by an organization, avoid changing settings you do not control; managed configurations may limit or override preference changes.
Why about:config changes need care
Mozilla warns that advanced preference changes can cause unexpected behavior and says it does not officially support using the Configuration Editor to modify preferences. Its Firefox advanced customization and configuration options article gives that general warning; it does not specifically endorse the Nova toggle. If changing the preference causes new problems, return it to its previous value if it is still available.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Choose the right approach for the customization
| Approach | What it affects | Support and trade-offs |
|---|---|---|
| Reported Nova preference | A reported switch for the Nova interface rollout | Community-reported and build-dependent; not confirmed by official Mozilla documentation. Changing advanced preferences can behave unexpectedly. |
| Built-in themes and customization | Colors, themes, and the ordinary customization options Firefox provides | Mozilla presents these as intended customization options. They are not established as a way to restore an earlier interface layout. |
| Custom CSS | Styling of interface components through profile CSS files | More technical and prone to breakage; Mozilla does not officially support custom style rules. It is separate from the Nova preference. |
Undo custom CSS separately
If the appearance change came from files you added yourself, rather than the Nova rollout, Mozilla documents a narrower rollback: set toolkit.legacyUserProfileCustomizations.stylesheets to false, then remove or rename userChrome.css or userContent.css in the Firefox profile’s chrome folder. Follow Mozilla’s guidance on advanced customization and configuration. This addresses custom CSS, not Nova itself.
Why Refresh Firefox is not the first fix to try
Refresh Firefox is a broader reset, not a Nova-specific rollback. Mozilla says it removes add-ons, extension data, and preference configurations, so it can undo more customization than intended. Consider it only if you are troubleshooting wider Firefox problems and understand what will be removed; Mozilla explains the effects in its Refresh Firefox guide.
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