312207 2026-04-13 16:51:14 -0700 [Site Isolation] http/tests/misc/iframe-beforeunload-dialog-not-matching-ancestor-securityorigin.html doesn't log that it cannot dispatch a beforeUnload event to cross origin frames 2026-05-19 10:02:53 -0700 1 1 1 Unclassified WebKit Page Loading WebKit Nightly Build Unspecified Unspecified RESOLVED FIXED InRadar P2 Normal --- 1 a.tarbinian webkit-unassigned beidson webkit-bug-importer oldest_to_newest 2199943 0 a.tarbinian 2026-04-13 16:51:14 -0700 When running http/tests/misc/iframe-beforeunload-dialog-not-matching-ancestor-securityorigin.html with site isolation enabled, WebKit does not log the following message: "Blocked attempt to show beforeunload confirmation dialog on behalf of a frame with different security origin." For context, the beforeUnload event gets run before a frame is about to be unloaded. The main use case for this event is to provide the user with a confirmation dialog to avoid closing the page and losing unsaved work. In FrameLoader::shouldClose, this message gets logged when a frame is about to be closed and WebKit is about to dispatch a beforeUnload message to each descendant frame of the navigating frame. However, in the current implementation it only collects LocalFrames to dispatch to. https://github.com/WebKit/WebKit/blob/723bdacf3bed4568822c50a02226c7fb115a487b/Source/WebCore/loader/FrameLoader.cpp#L3878-L3901 Under site isolation, cross-origin RemoteFrames were silently skipped and the console message was never emitted. 2199944 1 webkit-bug-importer 2026-04-13 16:51:20 -0700 <rdar://problem/174697142> 2200304 2 a.tarbinian 2026-04-14 12:11:25 -0700 Pull request: https://github.com/WebKit/WebKit/pull/62756 2212093 3 ews-feeder 2026-05-19 10:02:51 -0700 Committed 313493@main (7254a2893c2e): <https://commits.webkit.org/313493@main> Reviewed commits have been landed. Closing PR #62756 and removing active labels.