topic Firefox Nightly shows a blank window with legacy default UI styling before loading the current new UI on startup in Discussions https://connect.mozilla.org/t5/discussions/firefox-nightly-shows-a-blank-window-with-legacy-default-ui/m-p/134389#M54081 <P>I am using Firefox Nightly version 155.0a1 on Windows 11 24H2.</P><P>On every cold start, Firefox briefly displays a blank window whose default styling matches the legacy UI rather than the current new UI shipped in this build. After a short moment, it correctly switches to the new UI.</P><P>Please let me know if any further logs (about:support, startup logs) are needed. <span class="lia-unicode-emoji" title=":slightly_smiling_face:">🙂</span></P> Mon, 10 Aug 2026 12:29:24 GMT RavenVI 2026-08-10T12:29:24Z Firefox Nightly shows a blank window with legacy default UI styling before loading the current new UI on startup https://connect.mozilla.org/t5/discussions/firefox-nightly-shows-a-blank-window-with-legacy-default-ui/m-p/134389#M54081 <P>I am using Firefox Nightly version 155.0a1 on Windows 11 24H2.</P><P>On every cold start, Firefox briefly displays a blank window whose default styling matches the legacy UI rather than the current new UI shipped in this build. After a short moment, it correctly switches to the new UI.</P><P>Please let me know if any further logs (about:support, startup logs) are needed. <span class="lia-unicode-emoji" title=":slightly_smiling_face:">🙂</span></P> Mon, 10 Aug 2026 12:29:24 GMT https://connect.mozilla.org/t5/discussions/firefox-nightly-shows-a-blank-window-with-legacy-default-ui/m-p/134389#M54081 RavenVI 2026-08-10T12:29:24Z