ToDo: diffs FF141-FF142

[earthlng]

FF142 release date: Aug. 19th 2025

FF142 release notes
FF142 for developers
FF142 security advisories

---

101 diffs ( 55 new, 33 gone, 13 different )

changed in v142.0:

• 2662 pref("extensions.webextensions.restrictedDomains",

  •  now: "accounts-static.cdn.mozilla.net,accounts.firefox.com,addons.cdn.mozilla.net,addons.mozilla.org,api.accounts.firefox.com,content.cdn.mozilla.net,discovery.addons.mozilla.org,oauth.accounts.firefox.com,profile.accounts.firefox.com,support.mozilla.org,sync.services.mozilla.com");
    prev: "accounts-static.cdn.mozilla.net,accounts.firefox.com,addons.cdn.mozilla.net,addons.mozilla.org,api.accounts.firefox.com,content.cdn.mozilla.net,discovery.addons.mozilla.org,install.mozilla.org,oauth.accounts.firefox.com,profile.accounts.firefox.com,support.mozilla.org,sync.services.mozilla.com"
    

• 1224 pref("security.pki.crlite_mode", 2); // prev: 3

---

ignore

click me for details

==NEW

pref("browser.crashReports.dontShowBefore", 0);
pref("browser.link.alternative_click.block_javascript", true);
pref("browser.ml.chat.maxLength", 7000);
pref("browser.newtabpage.activity-stream.discoverystream.placements.contextualBanners", "");
pref("browser.newtabpage.activity-stream.discoverystream.placements.contextualBanners.counts", "");
pref("browser.newtabpage.activity-stream.feeds.listsfeed", true);
pref("browser.newtabpage.activity-stream.feeds.timerfeed", true);
pref("browser.newtabpage.activity-stream.widgets.focusTimer.enabled", true);
pref("browser.newtabpage.activity-stream.widgets.lists.enabled", true);
pref("browser.newtabpage.activity-stream.widgets.system.focusTimer.enabled", false);
pref("browser.newtabpage.activity-stream.widgets.system.lists.enabled", false);
pref("browser.newtabpage.resource-mapping.log", false);
pref("browser.newtabpage.trainhopAddon.xpiBaseURL", "https://archive.mozilla.org/pub/system-addons/newtab/");
pref("browser.tabs.groups.smart.searchTopicEnabled", true);
pref("browser.urlbar.merino.ohttpConfigURL", "");
pref("browser.urlbar.merino.ohttpRelayURL", "");
pref("dom.document.name_getter_prevent_shadowing.enabled", false);
pref("dom.element.commandfor.on_details.enabled", false);
pref("dom.object_embed.codebase.enabled", false);
pref("dom.quotaManager.loadQuotaFromSecondaryCache", false);
pref("dom.quotaManager.originInitialization.updateOriginMetadata", false);
pref("dom.urlpattern.enabled", true);
pref("dom.webnotifications.icon_encoding_utf8.enabled", true);
pref("extensions.formautofill.creditCards.os-auth.locked.enabled", false);
pref("gfx.webrender.dithering", false);
pref("gfx.webrender.layer-compositor", false);
pref("gfx.webrender.layer-compositor-force-composition-surface", false);
pref("layout.css.heading-selector.enabled", false);
pref("layout.css.typed-om.enabled", false);
pref("layout.testing.scrollbars.always-hidden", false);
pref("mathml.unknown_mrow.enabled", true);
pref("media.getusermedia.camera.fake.force", false);
pref("media.hardware-video-encoding.enabled", true);
pref("media.hardware-video-encoding.force-enabled", false);
pref("media.navigator.video.default_resize_mode", 0);
pref("media.navigator.video.resize_mode.enabled", false);
pref("network.cookie.skip_browsing_context_check_in_parent_for_testing", false);
pref("network.http.http3.max_gso_segments", 1);
pref("network.lna.address_space.local.override", "");
pref("network.lna.address_space.private.override", "");
pref("network.lna.address_space.public.override", "");
pref("nimbus.profilesdatastoreservice.sync.enabled", false);
pref("privacy.trackingprotection.allow_list.hasMigratedCategoryPrefs", false);
pref("security.integrity_policy.stylesheet.enabled", false);
pref("sidebar.installed.extensions", "");
pref("signon.management.page.os-auth.locked.enabled", false);
pref("svg.image-element.force-sync-load", true);
pref("termsofuse.acceptedDate", "0");
pref("termsofuse.acceptedVersion", 0);
pref("termsofuse.bypassNotification", false);
pref("termsofuse.currentVersion", 4);
pref("termsofuse.minimumVersion", 4);
pref("widget.widnows.pen.override.number_of_preserver_value", 75);
pref("widget.windows.pen.tilt_override.enabled", false);
pref("widget.windows.pen.twist_override.enabled", false);

==REMOVED, RENAMED or HIDDEN

pref("devtools.netmonitor.response.ui.limit", 10240);
pref("dom.security.credentialmanagement.identity.heavyweight.enabled", false);
pref("dom.security.credentialmanagement.identity.lightweight.enabled", false);
pref("dom.security.enforceIPCBasedPrincipalVetting", true);
pref("dom.security.setdocumenturi", true);
pref("dom.svg.pathSegment.enabled", true);
pref("dom.viewTransitions.wr-old-capture", true);
pref("dom.workers.timeoutmanager", true);
pref("gfx.webrender.layer-compositor-use-composition-surface", true);
pref("layout.css.align-content.blocks.enabled", true);
pref("layout.css.animation-composition.enabled", true);
pref("layout.css.contain-intrinsic-size.enabled", true);
pref("layout.css.h1-in-section-ua-styles.enabled", false);
pref("layout.css.has-selector.enabled", true);
pref("layout.css.has-slotted-selector.enabled", true);
pref("layout.css.hyphenate-limit-chars.enabled", true);
pref("layout.css.import-supports.enabled", true);
pref("layout.css.overscroll-behavior.enabled", true);
pref("layout.css.text-indent-keywords.enabled", true);
pref("layout.css.text-wrap-balance.enabled", true);
pref("layout.css.transform-box-content-stroke.enabled", true);
pref("layout.display_partial_background_images", true);
pref("media.webspeech.recognition.force_enable", false);
pref("media.wmf.dxva.enabled", true);
pref("places.frecency.pages.alternative.maxDaysFromToday", 60);
pref("security.disallow_privileged_data_subdocuments_loads", true);
pref("security.disallow_privileged_https_script_loads", true);
pref("security.disallow_privileged_https_stylesheet_loads", true);
pref("security.disallow_privileged_https_subdocuments_loads", true);
pref("security.disallow_privileged_no_finaluri_loads", true);
pref("svg.nearestAndFarthestViewportElement.enabled", false);
pref("svg.use-element.data-url-href.allowed", false);
pref("widget.gtk.non-native-titlebar-buttons.enabled", true);

==CHANGED

pref("browser.newtabpage.activity-stream.discoverystream.placements.spocs", "newtab_stories_1, newtab_stories_2, newtab_stories_3, newtab_stories_4, newtab_stories_5, newtab_stories_6"); // prev: "newtab_spocs"
pref("browser.newtabpage.activity-stream.discoverystream.placements.spocs.counts", "1,1,1,1,1,1"); // prev: "6"
pref("browser.newtabpage.activity-stream.discoverystream.spoc-positions", "2,4,8,13,17,20"); // prev: "1,5,7,11,18,20"
pref("browser.newtabpage.activity-stream.support.url", "https://support.mozilla.org/1/firefox/142.0/WINNT/en-US/new-tab"); // prev: "https://support.mozilla.org/1/firefox/141.0/WINNT/en-US/new-tab"
pref("browser.newtabpage.activity-stream.system.showSponsoredCheckboxes", true); // prev: false
pref("browser.urlbar.deduplication.enabled", true); // prev: false
pref("dom.animations.commit-styles-endpoint-inclusive", true); // prev: false
pref("dom.enable_web_task_scheduling", true); // prev: false
pref("dom.shadowdom.selection_across_boundary.enabled", true); // prev: false
pref("javascript.options.wasm_unroll_loops", true); // prev: false
pref("network.cookie.chips.partitionLimitDryRun", false); // prev: true

[earthlng]

some bugzilla tickets

• browser.crashReports.dontShowBefore
  Bug 1853108 - Fix wording and add a one week guard for Crash Pull

• browser.link.alternative_click.block_javascript
  Bug 672618 - Don't execute javascript: URLs on CTRL+click, middle-click etc.

• browser.ml.chat.maxLength
  Bug 1958088 - Make the AI chatbot selection character limit configurable

• browser.newtabpage.activity-stream.discoverystream.placements.contextualBanners
  Bug 1974908 - Send section topic above AdBanner to UAPI.
  Revert "Bug 1974908 - Send section topic above AdBanner to UAPI.

• browser.newtabpage.activity-stream.discoverystream.placements.contextualBanners.counts
  Bug 1974908 - Send section topic above AdBanner to UAPI.
  Revert "Bug 1974908 - Send section topic above AdBanner to UAPI.

• browser.newtabpage.activity-stream.discoverystream.placements.spocs
  Bug 1978081 – New ads positions & placements - Ride the trains.

• browser.newtabpage.activity-stream.discoverystream.placements.spocs.counts
  Bug 1978081 – New ads positions & placements - Ride the trains.

• browser.newtabpage.activity-stream.discoverystream.spoc-positions
  Bug 1978081 – New ads positions & placements - Ride the trains.

• browser.newtabpage.resource-mapping.log
  Bug 1973104 - Move resource mapping routine from builtin-newtab into core Firefox.
  Revert "Bug 1973104 - Move resource mapping routine from builtin-newtab into core Firefox.

• browser.newtabpage.trainhopAddon.xpiBaseURL
  Bug 1973228 - Use Nimbus to download and install a signed NewTab XPI.

• browser.tabs.groups.smart.searchTopicEnabled
  Bug 1961086 - search suggest

• browser.urlbar.deduplication.enabled
  Bug 1979658 - Enable urlbar deduplication by default.

• browser.urlbar.merino.ohttpConfigURL
  Bug 1974103 - Allow Merino requests to be sent over OHTTP.

• browser.urlbar.merino.ohttpRelayURL
  Bug 1974103 - Allow Merino requests to be sent over OHTTP.

• devtools.netmonitor.response.ui.limit
  Bug 1976893 - [devtools] Remove unused preference devtools.netmonitor.response.ui.limit

• dom.animations.commit-styles-endpoint-inclusive
  Bug 1973203 - Enable commitStyles behavior by default on release channels.

• dom.document.name_getter_prevent_shadowing.enabled
  Bug 1976243 - Prevent shadowing of document properties in Nightly.

• dom.element.commandfor.on_details.enabled
  Bug 1867785 - Move details commandfor commands behind flag

• dom.enable_web_task_scheduling
  Bug 1966997 - Enable Prioritized Task Scheduling API in Release

• dom.object_embed.codebase.enabled
  Bug 1973900 - Remove support for the codebase attribute from .

• dom.quotaManager.loadQuotaFromSecondaryCache
  Bug 1982790 - QM: Enable L2 quota info cache unconditionally;
  Bug 1978609 - QM: Enable origin metadata updates and use of L2 quota info cache on all Nightly platforms;
  Bug 1976451 - QM: Enable origin metadata updates and use of L2 quota info cache on all desktop Nightly platforms;
  Bug 1973433 - QM: Enable use of L2 quota info cache during repository initialization on Nightly and Linux;
  Bug 1973429 - QM: Add pref to control use of L2 quota info cache during repository initialization;

• dom.quotaManager.originInitialization.updateOriginMetadata
  Bug 1982790 - QM: Enable L2 quota info cache unconditionally;
  Bug 1978609 - QM: Enable origin metadata updates and use of L2 quota info cache on all Nightly platforms;
  Bug 1976451 - QM: Enable origin metadata updates and use of L2 quota info cache on all desktop Nightly platforms;
  Bug 1973422 - QM: Enable origin metadata file updates after initialization on Nightly and Linux;
  Bug 1972548 - QM: Add pref to control origin metadata file updates after initialization;

• dom.security.credentialmanagement.identity.heavyweight.enabled
  Bug 1977633 - Remove unused FedCM prefs.
  Bug 1969015 - Remove Lightweight FedCM specific codepaths, to be integrated in directly with full FedCM -
  Revert "Bug 1969015, 1969017: apply code formatting via Lando" for causing WPT failures @lfedcm-identity.create-store-collect.tentative.sub.https.html
  Revert "Bug 1969015, 1969017: apply code formatting via Lando" for causing failures complaining about fedcm-no-registered-idps.https.html.
  Revert "Bug 1969015, 1969017: apply code formatting via Lando" for causing leaks @ mochitest.toml
  Revert "Bug 1969015, 1969017: apply code formatting via Lando" for causing build bustages

• dom.security.credentialmanagement.identity.lightweight.enabled
  Bug 1977633 - Remove unused FedCM prefs.

• dom.security.enforceIPCBasedPrincipalVetting
  Bug 1873342 - Remove the dom.security.enforceIPCBasedPrincipalVetting pref.

• dom.security.setdocumenturi
  Bug 1974417 - Remove the dom.security.setdocumenturi preference.

• dom.shadowdom.selection_across_boundary.enabled
  Bug 1903870 - Enable dom.shadowdom.selection_across_boundary.enabled in Release

• dom.svg.pathSegment.enabled
  Bug 1977772 - Remove dom.svg.pathSegment.enabled pref

• dom.urlpattern.enabled
  Bug 1731418 - Put URLPattern api behind a pref
  Revert "Bug 1731418 - Expose URLPattern to worker and service worker interface.

• dom.viewTransitions.wr-old-capture
  Bug 1973455 - Remove the fallback code for old state captures.
  Revert "Bug 1971558, 1972255, 1973455: apply code formatting via Lando" for causing BP bustages @ViewTransition.cpp

• dom.webnotifications.icon_encoding_utf8.enabled
  Bug 1961846 - Use UTF8 for notification icon URLs

• dom.workers.timeoutmanager
  Bug 1965514 - Remove dom.workers.timeoutmanager pref and unused code,
  Revert "Bug 1965514 - Remove dom.workers.timeoutmanager pref and unused code,

• extensions.formautofill.creditCards.os-auth.locked.enabled
  Bug 1970507 - Disable OS Auth by default.
  Bug 1960092 - P2: Remove getSecurePref and setSecurePref in FormAutofillUtils.
  Revert "Bug 1970507 - Disable OS Auth by default.

• extensions.webextensions.restrictedDomains
  Bug 1973697 - remove install.mozilla.org from extensions.webextensions.restrictedDomains preference.

• gfx.webrender.dithering
  Bug 1986901 - Let hardware WebRender dithering of gradient ride the trains
  Bug 1984549 - Enable hardware WebRender linear gradient dithering in Nightly
  Bug 1971925 - Add a capability to enable dithering in hardware WebRender

• gfx.webrender.layer-compositor
  Bug 1945683 - Enable layer compositor on Windows in Nightly
  Bug 1976135 - Remove nightly only limitation of pref gfx.webrender.layer-compositor
  Bug 1973147 - Use DCSwapChain instead of DCLayerCompositionSurface when overlay does not exist
  Revert "Bug 1945683 - Enable layer compositor on Windows in Nightly

• gfx.webrender.layer-compositor-force-composition-surface
  Bug 1973147 - Use DCSwapChain instead of DCLayerCompositionSurface when overlay does not exist

• gfx.webrender.layer-compositor-use-composition-surface
  Bug 1973147 - Use DCSwapChain instead of DCLayerCompositionSurface when overlay does not exist

• javascript.options.wasm_unroll_loops
  Bug 1976409 - Re-enable wasm loop unrolling for non-nightly builds.
  Bug 1972357 - Disable wasm loop unrolling in Fx 140.

• layout.css.align-content.blocks.enabled
  Bug 1977267 - Remove layout.css.align-content.blocks.enabled.

• layout.css.animation-composition.enabled
  Bug 1977696: Remove about:config pref layout.css.animation-composition.enabled.

• layout.css.contain-intrinsic-size.enabled
  Bug 1977696: Remove about:config pref layout.css.contain-intrinsic-size.enabled.

• layout.css.h1-in-section-ua-styles.enabled
  Bug 1976196 - Remove h1-in-section styles.

• layout.css.has-selector.enabled
  Bug 1977004: Remove about:config pref layout.css.has-selector.enabled which has been default-enabled for many releases.

• layout.css.has-slotted-selector.enabled
  Bug 1977004: Remove about:config pref layout.css.has-slotted-selector.enabled which has been default-enabled for many releases.

• layout.css.heading-selector.enabled
  Bug 1974386 - Implement :heading & :heading() selectors

• layout.css.hyphenate-limit-chars.enabled
  Bug 1977696: Remove about:config pref layout.css.hyphenate-limit-chars.enabled.

• layout.css.import-supports.enabled
  Bug 1898425 - Remove layout.css.import-supports.enabled pref
  Revert "Bug 1898425 - Remove layout.css.import-supports.enabled pref

• layout.css.overscroll-behavior.enabled
  Bug 1977696: Remove about:config pref layout.css.overscroll-behavior.enabled.

• layout.css.text-indent-keywords.enabled
  Bug 1977696: Remove about:config pref layout.css.text-indent-keywords.enabled.

• layout.css.text-wrap-balance.enabled
  Bug 1977696: Remove about:config pref layout.css.text-wrap-balance.enabled.

• layout.css.transform-box-content-stroke.enabled
  Bug 1977696: Remove about:config pref layout.css.transform-box-content-stroke.enabled.

• layout.css.typed-om.enabled
  Bug 1976441 - Add a pref for experimental CSS Typed OM support;

• layout.display_partial_background_images
  Bug 1911943 - Remove layout.display_partial_background_images pref

• layout.testing.scrollbars.always-hidden
  Bug 1975949 - Add a testing pref to always hide scrollbars.

• mathml.unknown_mrow.enabled
  Bug 1958853 - Render unknown MathML elements as an mrow.

• media.getusermedia.camera.fake.force
  Bug 1973816 - Expose the fake video source as a regular camera backend with two capabilities under a pref.
  Revert "Bug 1973816 - Expose the fake video source as a regular camera backend with two capabilities under a pref.
  Revert "Bug 1973816 - Expose the fake video source as a real camera backend with two capabilities under a pref.

• media.hardware-video-encoding.enabled
  Bug 1972902 - Part 3. Add support for blocklisting hardware video encoding.
  Revert "Bug 1972902: apply code formatting via Lando" for causing xpc crash failures
  Revert "Bug 1972902: apply code formatting via Lando" for causing tsan mass failures.

• media.hardware-video-encoding.force-enabled
  Bug 1972902 - Part 3. Add support for blocklisting hardware video encoding.
  Revert "Bug 1972902: apply code formatting via Lando" for causing xpc crash failures
  Revert "Bug 1972902: apply code formatting via Lando" for causing tsan mass failures.

• media.navigator.video.default_resize_mode
  Bug 1286945 - Enable the resizeMode constraint and make the default value "crop-and-scale".
  Revert "Bug 1286945 - Remove the unused DEFAULT_AUDIO_TIMER_MS" for causing Fenix anc Focus failures on SitePermissionsTest#allowCameraPermissionsTest
  Bug 1433480 - Implement resizeMode constraint (in anticipation of downscaling).

• media.navigator.video.resize_mode.enabled
  Bug 1286945 - Enable the resizeMode constraint and make the default value "crop-and-scale".
  Revert "Bug 1286945 - Remove the unused DEFAULT_AUDIO_TIMER_MS" for causing Fenix anc Focus failures on SitePermissionsTest#allowCameraPermissionsTest
  Bug 1433480 - Hide resizeMode constraint/setting/capability behind a pref.

• media.webspeech.recognition.force_enable
  Bug 1975468 - Remove bogus "speech-recognition" permission check that is never set

• media.wmf.dxva.enabled
  Bug 1972902 - Part 1. Streamline hardware video support configuration in gfxPlatform.

• network.cookie.chips.partitionLimitDryRun
  Bug 1971595 - Disable CHIPS dry-run purging

• network.cookie.skip_browsing_context_check_in_parent_for_testing
  Bug 1977803 - Move network.cookie.skip_browsing_context_check_in_parent_for_testing to staticpref,

• network.http.http3.max_gso_segments
  Bug 1979279 - disable QUIC GSO on Windows
  Bug 1975873 - update neqo to v0.14.1

• network.lna.address_space.local.override
  Bug 1968192 - Add prefs and NetAddr support for IpAddressSpace Overrides.
  Revert (Bug 1968192, Bug 1974504) - for causing build bustages @nsIOService.cpp.

• network.lna.address_space.private.override
  Bug 1968192 - Add prefs and NetAddr support for IpAddressSpace Overrides.
  Revert (Bug 1968192, Bug 1974504) - for causing build bustages @nsIOService.cpp.

• network.lna.address_space.public.override
  Bug 1968192 - Add prefs and NetAddr support for IpAddressSpace Overrides.
  Revert (Bug 1968192, Bug 1974504) - for causing build bustages @nsIOService.cpp.

• nimbus.profilesdatastoreservice.sync.enabled
  Bug 1956086 - Unenroll from experiments that have unenrolled in other profiles in a group

• places.frecency.pages.alternative.maxDaysFromToday
  Bug 1980729 - Remove visit date filter from alt frecency SQL query -

• privacy.trackingprotection.allow_list.hasMigratedCategoryPrefs
  Bug 1974449 - Add a migration for url classifier allow-list categories for ETP 'strict' and 'custom' users.
  Revert "Bug 1974449 - Add tests for category prefs migration.

• security.disallow_privileged_data_subdocuments_loads
  Bug 1973227 - part 1: remove disallowed privileged load prefs and keep defaults

• security.disallow_privileged_https_script_loads
  Bug 1973227 - part 1: remove disallowed privileged load prefs and keep defaults

• security.disallow_privileged_https_stylesheet_loads
  Bug 1973227 - part 1: remove disallowed privileged load prefs and keep defaults

• security.disallow_privileged_https_subdocuments_loads
  Bug 1973227 - part 1: remove disallowed privileged load prefs and keep defaults

• security.disallow_privileged_no_finaluri_loads
  Bug 1973227 - part 1: remove disallowed privileged load prefs and keep defaults

• security.integrity_policy.stylesheet.enabled
  Bug 1976656 - Enable Integrity-Policy by default for scripts.
  Revert "Bug 1976656 - Enable Integrity-Policy by default for scripts.
  Bug 1974247 - Extend integrity policy to stylesheets.

• security.pki.crlite_mode
  Bug 1974052 - switch CRLite mode to enforce.

• sidebar.installed.extensions
  Bug 1944719 - Make sidebar extensions removeable from launcher
  Revert "Bug 1944719 - Make sidebar extensions removeable from launcher

• signon.management.page.os-auth.locked.enabled
  Bug 1970507 - Disable OS Auth by default.
  Bug 1960092 - P1: Remove getSecurePref and setSecurePref in LoginHelper.
  Revert "Bug 1970507 - Disable OS Auth by default.

• svg.image-element.force-sync-load
  Bug 1967531 - Unify SVG image and HTML image loading

• svg.nearestAndFarthestViewportElement.enabled
  Bug 1977769 - Remove nearestViewportElement and farthestViewportElement

• svg.use-element.data-url-href.allowed
  Bug 1977645 - Remove svg.use-element.data-url-href.allowed pref.

• widget.gtk.non-native-titlebar-buttons.enabled
  Bug 1974137 - Remove unused widget.gtk.non-native-titlebar-buttons.enabled pref

• widget.widnows.pen.override.number_of_preserver_value
  Bug 1976088 - Make the copy constructor of dom::Touch call the copy constructor of WidgetPointerHelper

• widget.windows.pen.tilt_override.enabled
  Bug 1976088 - Make the copy constructor of dom::Touch call the copy constructor of WidgetPointerHelper

• widget.windows.pen.twist_override.enabled
  Bug 1976088 - Make the copy constructor of dom::Touch call the copy constructor of WidgetPointerHelper