Found on Ubuntu 16.04 with m-c 20170608162720 e61060be364 This test case requires fuzzPriv plugin. It should also work with enabling screen reader enabled. Assertion failure: owned (IsRelocated flag is out of sync with mARIAOwnsHash), at /home/worker/workspace/build/src/accessible/generic/DocAccessible.cpp:2208 #0 0x7f20a04be6db in mozilla::a11y::DocAccessible::MoveChild(mozilla::a11y::Accessible*, mozilla::a11y::Accessible*, int) src/accessible/generic/DocAccessible.cpp:2219:40 #1 0x7f20a04bdabb in mozilla::a11y::DocAccessible::DoARIAOwnsRelocation(mozilla::a11y::Accessible*) src/accessible/generic/DocAccessible.cpp:2127:9 #2 0x7f20a0465df2 in mozilla::a11y::NotificationController::WillRefresh(mozilla::TimeStamp) src/accessible/base/NotificationController.cpp:809:18 #3 0x7f209e2ff870 in nsRefreshDriver::Tick(long, mozilla::TimeStamp) src/layout/base/nsRefreshDriver.cpp:1831:12 #4 0x7f209e308c2e in mozilla::RefreshDriverTimer::TickRefreshDrivers(long, mozilla::TimeStamp, nsTArray<RefPtr<nsRefreshDriver> >&) src/layout/base/nsRefreshDriver.cpp:301:7 #5 0x7f209e3089fd in mozilla::RefreshDriverTimer::Tick(long, mozilla::TimeStamp) src/layout/base/nsRefreshDriver.cpp:322:5 #6 0x7f209e30c875 in mozilla::VsyncRefreshDriverTimer::RunRefreshDrivers(mozilla::TimeStamp) src/layout/base/nsRefreshDriver.cpp:754:5 #7 0x7f209e30b366 in mozilla::VsyncRefreshDriverTimer::RefreshDriverVsyncObserver::TickRefreshDriver(mozilla::TimeStamp) src/layout/base/nsRefreshDriver.cpp:667:35 #8 0x7f209e307007 in mozilla::VsyncRefreshDriverTimer::RefreshDriverVsyncObserver::ParentProcessVsyncNotifier::Run() src/layout/base/nsRefreshDriver.cpp:513:20 #9 0x7f2098caa35f in nsThread::ProcessNextEvent(bool, bool*) src/xpcom/threads/nsThread.cpp:1406:14 #10 0x7f2098cb4d20 in NS_ProcessNextEvent(nsIThread*, bool) src/xpcom/threads/nsThreadUtils.cpp:472:10 #11 0x7f2099802075 in mozilla::ipc::MessagePump::Run(base::MessagePump::Delegate*) src/ipc/glue/MessagePump.cpp:96:21 #12 0x7f209974e8e7 in MessageLoop::RunInternal() src/ipc/chromium/src/base/message_loop.cc:238:10 #13 0x7f209974e779 in MessageLoop::Run() src/ipc/chromium/src/base/message_loop.cc:211:3 #14 0x7f209de20c2a in nsBaseAppShell::Run() src/widget/nsBaseAppShell.cpp:156:27 #15 0x7f20a0a21331 in nsAppStartup::Run() src/toolkit/components/startup/nsAppStartup.cpp:283:30 #16 0x7f20a0b7c6c2 in XREMain::XRE_mainRun() src/toolkit/xre/nsAppRunner.cpp:4569:22 #17 0x7f20a0b7e2fe in XREMain::XRE_main(int, char**, mozilla::BootstrapConfig const&) src/toolkit/xre/nsAppRunner.cpp:4749:8 #18 0x7f20a0b7f1e8 in XRE_main(int, char**, mozilla::BootstrapConfig const&) src/toolkit/xre/nsAppRunner.cpp:4844:21 #19 0x4eca88 in do_main(int, char**, char**) src/browser/app/nsBrowserApp.cpp:236:22 #20 0x4ec3a0 in main src/browser/app/nsBrowserApp.cpp:309:16 #21 0x7f20b58d482f in __libc_start_main /build/glibc-9tT8Do/glibc-2.23/csu/../csu/libc-start.c:291 #22 0x41e0d4 in _start (m-c-1496939240-asan-debug/firefox+0x41e0d4)

let's see if patch from bug 1369836 will help here

(In reply to alexander :surkov from comment #1) > let's see if patch from bug 1369836 will help here Looks like that fixed this issue as well. Tested with m-c Changeset: 16ffc1d05422a81099ce8b9b59de66dde4c8b2f0 Build ID: 20170728132457