313569 2026-04-28 13:40:25 -0700 [Site Isolation] COOP error reporting doesn't work 2026-05-04 13:05:38 -0700 1 1 1 Unclassified WebKit New Bugs WebKit Nightly Build Unspecified Unspecified RESOLVED FIXED InRadar P2 Normal --- 1 a.tarbinian webkit-unassigned webkit-bug-importer oldest_to_newest 2205463 0 a.tarbinian 2026-04-28 13:40:25 -0700 Several tests in imported/w3c/web-platform-tests/html/cross-origin-opener-policy/reporting/navigation-reporting are broken with site isolation enabled. These tests check that the browser is able to report a Cross-Origin-Reporing-Policy (COOP) violation. This is a feature which sends an HTTP POST request to a certain "reporting endpoint" when a COOP violation is detected https://w3c.github.io/reporting ​imported/w3c/web-platform-tests/html/cross-origin-opener-policy/reporting/navigation-reporting/report-only-four-reports.https.html imported/w3c/web-platform-tests/html/cross-origin-opener-policy/reporting/navigation-reporting/report-only-from-unsafe-none.https.html imported/w3c/web-platform-tests/html/cross-origin-opener-policy/reporting/navigation-reporting/report-only-same-origin-report-to.https.html imported/w3c/web-platform-tests/html/cross-origin-opener-policy/reporting/navigation-reporting/reporting-popup-same-origin-allow-popups-report-to.https.html imported/w3c/web-platform-tests/html/cross-origin-opener-policy/reporting/navigation-reporting/reporting-popup-same-origin-coep-report-to.https.html imported/w3c/web-platform-tests/html/cross-origin-opener-policy/reporting/navigation-reporting/reporting-popup-same-origin-report-to.https.html imported/w3c/web-platform-tests/html/cross-origin-opener-policy/reporting/navigation-reporting/reporting-popup-same-origin.https.html imported/w3c/web-platform-tests/html/cross-origin-opener-policy/reporting/navigation-reporting/reporting-popup-unsafe-none-report-to.https.html Here is the text diff from one of the tests: -PASS coop reporting test A test with both COOP and COOP report only setup to CROSS_ORIGIN with same-origin-allow-popups; report-to="coop-popup-report-endpoint", require-corp, same-origin; report-to="coop-popup-report-only-endpoint", require-corp +FAIL coop reporting test A test with both COOP and COOP report only setup to CROSS_ORIGIN with same-origin-allow-popups; report-to="coop-popup-report-endpoint", require-corp, same-origin; report-to="coop-popup-report-only-endpoint", require-corp promise_test: Unhandled rejection with value: "No report matched the expected report for endpoint: coop-report-endpoint, expected report: {\"body\":{\"disposition\":\"enforce\",\"effectivePolicy\":\"same-origin-allow-popups\",\"nextResponseURL\":\"/uuid=(uuid)$/\",\"type\":\"navigation-from-response\"},\"url\":\"https://web-platform.test:9443/html/cross-origin-opener-policy/reporting/navigation-reporting/report-only-four-reports.https.html\",\"type\":\"coop\"}, within available reports: []" PASS verify remaining reports This happens because the current WebKit code in WebPage::sendReportToEndpoints uses a LocalFrame to kick off the HTTP POST sequence. With site isolation, the frame being navigated can be a RemoteFrame which will cause the LocalFrame to be null and the HTTP Post will never be sent. 2205464 1 webkit-bug-importer 2026-04-28 13:40:31 -0700 <rdar://problem/175786872> 2205555 2 a.tarbinian 2026-04-28 16:31:44 -0700 Pull request: https://github.com/WebKit/WebKit/pull/63852 2207324 3 ews-feeder 2026-05-04 13:05:36 -0700 Committed 312548@main (61696c58623d): <https://commits.webkit.org/312548@main> Reviewed commits have been landed. Closing PR #63852 and removing active labels.