FF147 release date: Jan. 13th 2026
FF147 release notes
FF147 for developers
FF147 security advisories
151 diffs (63 new, 71 gone, 17 different)
new in 147.0:
pref("accessibility.anchorPositionedAsDetails.enabled", false);
pref("apz.async_scroll_css_anchor_pos", true);
pref("browser.aiwindow.enabled", false);
pref("browser.ipProtection.optedOut", false);
pref("browser.ml.chat.shortcut.onboardingMouseoverCount", 0);
pref("browser.newtabpage.activity-stream.discoverystream.imageProxy.enabled", false);
pref("browser.newtabpage.activity-stream.discoverystream.sections.clientLayout.enabled", false);
pref("browser.newtabpage.activity-stream.sov.amp.allocation", "100, 100, 100");
pref("browser.newtabpage.activity-stream.sov.enabled", false);
pref("browser.newtabpage.activity-stream.sov.frecency.allocation", "0, 0, 0");
pref("browser.newtabpage.activity-stream.sov.frecency.exposure", false);
pref("browser.newtabpage.activity-stream.sov.name", "SOV-20251122215625");
pref("browser.newtabpage.activity-stream.widgets.enabled", false);
pref("browser.newtabpage.activity-stream.widgets.maximized", false);
pref("browser.newtabpage.activity-stream.widgets.system.maximized", false);
pref("browser.translations.quickAction.enabled", false);
pref("dap.ohttp.hpke", "https://dap-09-3.api.divviup.org/ohttp-configs");
pref("dap.ohttp.relayURL", "https://mozilla-ohttp-dap.mozilla.fastly-edge.com/");
pref("devtools.jsonview.size-profiler.enabled", false);
pref("dom.about-blank-ckeditor-hack.disabled-domains", "");
pref("dom.about-blank-ckeditor-hack.enabled", false);
pref("dom.jsipc.send_typed", false);
pref("dom.navigation.api.internal_method_tracker", false);
pref("dom.quotaManager.temporaryStorage.clearNonPersistedZeroUsageOrigins", false);
pref("dom.quotaManager.temporaryStorage.initialOriginAccessTimeOffsetSec", 0);
pref("dom.quotaManager.temporaryStorage.maxOriginsToClearDuringCleanup", 150);
pref("dom.selection.exclude_non_selectable_nodes", false);
pref("extensions.webextensions.base-content-security-policy.v3-with-localhost", "script-src 'self' 'wasm-unsafe-eval' http://localhost:* http://127.0.0.1:*;");
pref("first-startup.category-tasks-enabled", true);
pref("gfx.canvas.accelerated.max-data-shmems", 400);
pref("intl.hyphenation-alias.ku-*", "ku");
pref("javascript.options.experimental.iterator_sequencing", true);
pref("layout.abspos.fragmentainer-aware-positioning.enabled", false);
pref("layout.css.anchor-positioning.position-try-order.enabled", false);
pref("layout.css.attr.enabled", false);
pref("layout.css.scroll-behavior.same-physics-as-user-input", false);
pref("layout.css.scroll-snap.damping-ratio", "1.0");
pref("layout.css.scroll-snap.spring-constant", "250.0");
pref("mathml.operator_dictionary_accent.disabled", false);
pref("media.video-queue.hw-accel-size", 3);
pref("network.buffer.default_size", 65536);
pref("network.http.http3.fallback_to_h2_on_error", true);
pref("network.http.http3.pmtud", false);
pref("network.http.rcwn.race_with_non_ssd", true);
pref("network.lna.prompt.timeout", 300000);
pref("network.trr_ui.fallback_was_checked", true);
pref("places.frecency.pages.halfLifeDays", 30);
pref("places.frecency.pages.highWeight", 100);
pref("places.frecency.pages.interactions.manyKeypresses", 50);
pref("places.frecency.pages.interactions.maxVisitGapSeconds", 120);
pref("places.frecency.pages.interactions.viewTimeIfManyKeypressesSeconds", 20);
pref("places.frecency.pages.interactions.viewTimeSeconds", 60);
pref("places.frecency.pages.lowWeight", 20);
pref("places.frecency.pages.mediumWeight", 50);
pref("places.frecency.pages.numSampledVisits", 10);
pref("places.frecency.pages.veryHighWeight", 200);
pref("places.semanticHistory.supportedRegions", "[["AU",["en-*"]],["CA",["en-*"]],["GB",["en-*"]],["IE",["en-*"]],["NZ",["en-*"]],["PH",["en-*"]],["US",["en-*"]]]");
pref("privacy.trackingprotection.harmfuladdon.enabled", true);
pref("security.webauthn.allow_with_certificate_override", false);
pref("services.sync.prefs.sync.privacy.trackingprotection.harmfuladdon.enabled", true);
pref("urlclassifier.features.harmfuladdon.blocklistTables", "harmfuladdon-block-digest256");
pref("urlclassifier.features.harmfuladdon.entitylistTables", "harmfuladdon-entitylist-digest256");
pref("widget.support-xdg-config", true);removed, renamed or hidden in 147.0:
pref("accessibility.windows.suppress-after-clipboard-copy", 2);
pref("accessibility.windows.suppress-for-snap-layout", 2);
pref("apz.android.chrome_fling_physics.friction", "0.015");
pref("apz.android.chrome_fling_physics.inflexion", "0.35");
pref("apz.android.chrome_fling_physics.stop_threshold", "0.1");
pref("apz.mac.enable_double_tap_zoom_touchpad_gesture", true);
pref("apz.windows.check_for_pan_gesture_conversion", true);
pref("apz.windows.force_disable_direct_manipulation", false);
pref("apz.windows.use_direct_manipulation", true);
pref("browser.display.windows.non_native_menus", 2);
pref("browser.newtabpage.activity-stream.discoverystream.spoc-topsites-positions", 2);
pref("browser.newtabpage.activity-stream.discoverystream.spocTopsitesAdTypes", "");
pref("browser.newtabpage.activity-stream.discoverystream.spocTopsitesPlacement.enabled", true);
pref("browser.newtabpage.activity-stream.discoverystream.spocTopsitesZoneIds", "");
pref("browser.newtabpage.activity-stream.feeds.trendingsearchfeed", true);
pref("browser.newtabpage.activity-stream.system.trendingSearch.enabled", false);
pref("browser.newtabpage.activity-stream.trendingSearch.defaultSearchEngine", "Google");
pref("browser.newtabpage.activity-stream.trendingSearch.enabled", true);
pref("browser.newtabpage.activity-stream.trendingSearch.variant", "");
pref("browser.search.suggest.ohttp.enabled", true);
pref("browser.search.suggest.ohttp.featureGate", false);
pref("browser.tabs.documentchannel.parent-controlled", false);
pref("browser.topsites.contile.sov.enabled", true);
pref("browser.urlbar.quicksuggest.dataCollection.enabled", false);
pref("devtools.selfxss.count", 0);
pref("devtools.toolbox.selectedTool", "inspector");
pref("dom.events.asyncClipboard.clipboardItem", true);
pref("dom.events.asyncClipboard.readText", true);
pref("dom.keyboardevent.dispatch_during_composition", true);
pref("dom.text_fragments.create_text_fragment.enabled", true);
pref("dom.webnotifications.icon_encoding_utf8.enabled", true);
pref("extensions.cookie.rejectWhenInvalid", true);
pref("gfx.android.rgb16.force", false);
pref("gfx.canvas.remote.use-draw-image-fast-path-d3d", true);
pref("gfx.compositor.gpu-migration", 1);
pref("gfx.core-animation.tint-opaque", false);
pref("gfx.direct3d11.allow-keyed-mutex", true);
pref("gfx.direct3d11.break-on-error", false);
pref("gfx.direct3d11.enable-debug-layer", false);
pref("gfx.direct3d11.reuse-decoder-device", true);
pref("gfx.direct3d11.reuse-decoder-device-force-enabled", false);
pref("gfx.direct3d11.sleep-on-create-device", 0);
pref("gfx.direct3d11.use-double-buffering", false);
pref("gfx.use-iosurface-textures", false);
pref("gfx.use-mutex-on-present", false);
pref("gfx.use-surfacetexture-textures", false);
pref("gfx.webrender.software.d3d11", true);
pref("gfx.webrender.software.d3d11.upload-mode", 4);
pref("gl.allow-high-power", true);
pref("gl.ignore-dx-interop2-blacklist", false);
pref("identity.fxaccounts.migrateToDevEdition", false);
pref("identity.fxaccounts.oauth.enabled", true);
pref("image.avif.enabled", true);
pref("intl.hyphenation-alias.kmr-*", "kmr");
pref("layers.d3d11.enable-blacklist", true);
pref("layers.d3d11.force-warp", false);
pref("layers.iosurfaceimage.recycle-limit", 15);
pref("layout.css.grid-multi-pass-track-sizing.enabled", true);
pref("layout.css.iframe-embedder-prefers-color-scheme.content.enabled", true);
pref("layout.css.scroll-behavior.damping-ratio", "1.0");
pref("layout.css.scroll-behavior.spring-constant", "250.0");
pref("network.auth.confirmAuth.enabled", false);
pref("network.dns.native_https_timeout_android", 20000);
pref("network.dns.native_https_timeout_mac_msec", 5000);
pref("prompts.modalType.confirmAuth", 2);
pref("security.webauthn.enable_macos_passkeys", true);
pref("webgl.dxgl.enabled", false);
pref("webgl.dxgl.needs-finish", false);
pref("webgl.prefer-16bpp", false);
pref("widget.android.use-surfacecontrol", false);
pref("widget.window-transforms.disabled", false);changed in 147.0:
pref("browser.contextual-services.contextId.rotation-in-days", 3); // 7
pref("browser.newtabpage.activity-stream.support.url", "https://support.mozilla.org/1/firefox/147.0/Linux/en-US/new-tab"); // https://support.mozilla.org/1/firefox/146.0/Linux/en-US/new-tab
pref("browser.safebrowsing.provider.google5.enabled", true); // false
pref("browser.safebrowsing.provider.mozilla.lists", "base-track-digest256,mozstd-trackwhite-digest256,google-trackwhite-digest256,content-track-digest256,mozplugin-block-digest256,mozplugin2-block-digest256,ads-track-digest256,social-track-digest256,analytics-track-digest256,base-fingerprinting-track-digest256,content-fingerprinting-track-digest256,base-cryptomining-track-digest256,content-cryptomining-track-digest256,fanboyannoyance-ads-digest256,fanboysocial-ads-digest256,easylist-ads-digest256,easyprivacy-ads-digest256,adguard-ads-digest256,social-tracking-protection-digest256,social-tracking-protection-facebook-digest256,social-tracking-protection-linkedin-digest256,social-tracking-protection-twitter-digest256,base-email-track-digest256,content-email-track-digest256,consent-manager-track-digest256,anti-fraud-track-digest256,harmfuladdon-block-digest256,harmfuladdon-entitylist-digest256"); // base-track-digest256,mozstd-trackwhite-digest256,google-trackwhite-digest256,content-track-digest256,mozplugin-block-digest256,mozplugin2-block-digest256,ads-track-digest256,social-track-digest256,analytics-track-digest256,base-fingerprinting-track-digest256,content-fingerprinting-track-digest256,base-cryptomining-track-digest256,content-cryptomining-track-digest256,fanboyannoyance-ads-digest256,fanboysocial-ads-digest256,easylist-ads-digest256,easyprivacy-ads-digest256,adguard-ads-digest256,social-tracking-protection-digest256,social-tracking-protection-facebook-digest256,social-tracking-protection-linkedin-digest256,social-tracking-protection-twitter-digest256,base-email-track-digest256,content-email-track-digest256,consent-manager-track-digest256,anti-fraud-track-digest256
pref("browser.tabs.dragDrop.multiselectStacking", true); // false
pref("dom.keyboardevent.init_key_event.enabled_in_addons", false); // true
pref("dom.navigation.webidl.enabled", true); // false
pref("dom.storage_access.headers.enabled", true); // false
pref("gfx.webrender.precise-conic-gradients-swgl", true); // false
pref("gfx.webrender.precise-radial-gradients-swgl", true); // false
pref("javascript.options.inlining_bytecode_max_length", 140); // 130
pref("javascript.options.use_js_microtask_queue", true); // false
pref("layout.css.anchor-positioning.enabled", true); // false
pref("layout.css.module-scripts.enabled", true); // false
pref("network.http.dictionaries.enable", true); // false
pref("network.http.rcwn.enabled", false); // true
pref("network.trr.retry_on_recoverable_errors", false); // true
ignore
click me for details
==NEW
==REMOVED, RENAMED or HIDDEN
==CHANGED
FF147 release date: Jan. 13th 2026
FF147 release notes
FF147 for developers
FF147 security advisories
151 diffs (63 new, 71 gone, 17 different)
new in 147.0:
removed, renamed or hidden in 147.0:
changed in 147.0:
ignore
click me for details
==NEW
==REMOVED, RENAMED or HIDDEN
==CHANGED