The following 7 API-tests are crashing/hitting an assertion on iOS Debug: TestWebKitAPI.AnimatedResize.ChangeFrameAndMinimumEffectiveDeviceWidthDuringAnimatedResize TestWebKitAPI.AnimatedResize.OverrideLayoutSizeChangesDuringAnimatedResizeSucceed TestWebKitAPI.AnimatedResize.ResizeWithContentHiddenCompletes TestWebKitAPI.AnimatedResize.ResizeWithContentHiddenWithSubsequentNoOpResizeCompletes TestWebKitAPI.AnimatedResize.AnimatedResizeBlocksDoAfterNextPresentationUpdate TestWebKitAPI.AnimatedResize.AnimatedResizeBlocksViewportFitChanges TestWebKitAPI.RestoreScrollPositionTests.RestoreScrollPositionDuringResize HISTORY: https://results.webkit.org/?suite=api-tests&suite=api-tests&suite=api-tests&suite=api-tests&suite=api-tests&suite=api-tests&suite=api-tests&test=TestWebKitAPI.AnimatedResize.ChangeFrameAndMinimumEffectiveDeviceWidthDuringAnimatedResize&test=TestWebKitAPI.AnimatedResize.OverrideLayoutSizeChangesDuringAnimatedResizeSucceed&test=TestWebKitAPI.AnimatedResize.ResizeWithContentHiddenCompletes&test=TestWebKitAPI.AnimatedResize.ResizeWithContentHiddenWithSubsequentNoOpResizeCompletes&test=TestWebKitAPI.AnimatedResize.AnimatedResizeBlocksDoAfterNextPresentationUpdate&test=TestWebKitAPI.AnimatedResize.AnimatedResizeBlocksViewportFitChanges&test=TestWebKitAPI.RestoreScrollPositionTests.RestoreScrollPositionDuringResize Assertion/Crash TEXT: ASSERTION FAILED: scale == [webView->_scrollView zoomScale] /Volumes/Data/worker/Apple-iOS-16-Simulator-Debug-Build/build/Source/WebKit/UIProcess/API/ios/WKWebViewIOS.mm(567) : CGFloat contentZoomScale(WKWebView *) 1 0x1152380d9 WTFCrash 2 0x1349681cb WTFCrashWithInfo(int, char const*, char const*, int) 3 0x135e31601 contentZoomScale(WKWebView*) 4 0x135e47821 -[WKWebView(WKPrivateIOS) _beginAnimatedResizeWithUpdates:] 5 0x103f334ac AnimatedResize_ChangeFrameAndMinimumEffectiveDeviceWidthDuringAnimatedResize_Test::TestBody() 6 0x10493668b void testing::internal::HandleSehExceptionsInMethodIfSupported<testing::Test, void>(testing::Test*, void (testing::Test::*)(), char const*) 7 0x10490d19a void testing::internal::HandleExceptionsInMethodIfSupported<testing::Test, void>(testing::Test*, void (testing::Test::*)(), char const*) 8 0x10490d0e3 testing::Test::Run() 9 0x10490e121 testing::TestInfo::Run() 10 0x10490f1a4 testing::TestSuite::Run() 11 0x10491d89c testing::internal::UnitTestImpl::RunAllTests() 12 0x10493aa3b bool testing::internal::HandleSehExceptionsInMethodIfSupported<testing::internal::UnitTestImpl, bool>(testing::internal::UnitTestImpl*, bool (testing::internal::UnitTestImpl::*)(), char const*) 13 0x10491d27a bool testing::internal::HandleExceptionsInMethodIfSupported<testing::internal::Uni tTestImpl, bool>(testing::internal::UnitTestImpl*, bool (testing::internal::UnitTestImpl::*)(), char const*) 14 0x10491d165 testing::UnitTest::Run() 15 0x103f296d1 RUN_ALL_TESTS() 16 0x103f29666 TestWebKitAPI::TestsController::run(int, char**) 17 0x1048e12dc main 18 0x1076902bf (null) 19 0x11518352e (null) Child process terminated with signal 11: Segmentation fault https://build.webkit.org/#/builders/663/builds/568/steps/18/logs/stdio I was able to reproduce all of these assertions/crashes by running the test as follows: run-api-tests <insert_test_name_here> I was able to reproduce the crash as far back as 258307@main, but all tests passed when ran at 258306@main. So it appears that 258307@main is our culprit.