This bug is for crash report bp-d3edca6f-7830-4980-ae4c-a1b320190619.

Top 10 frames of crashing thread:

0 xul.dll mozilla::dom::ContentParent::RecvDetachBrowsingContextChildren dom/ipc/ContentParent.cpp:5850
1 xul.dll mozilla::dom::PContentParent::OnMessageReceived ipc/ipdl/PContentParent.cpp:10639
2 xul.dll mozilla::ipc::MessageChannel::DispatchMessage ipc/glue/MessageChannel.cpp:2082
3 xul.dll mozilla::ipc::MessageChannel::MessageTask::Run ipc/glue/MessageChannel.cpp:1970
4 xul.dll nsThread::ProcessNextEvent xpcom/threads/nsThread.cpp:1225
5 xul.dll NS_ProcessNextEvent xpcom/threads/nsThreadUtils.cpp:486
6 xul.dll void mozilla::ipc::MessagePump::Run ipc/glue/MessagePump.cpp:88
7 xul.dll MessageLoop::RunHandler ipc/chromium/src/base/message_loop.cc:308
8 xul.dll MessageLoop::Run ipc/chromium/src/base/message_loop.cc:290
9 xul.dll nsBaseAppShell::Run widget/nsBaseAppShell.cpp:137

Affected Versions:

• Firefox 69.0a1 (BuildId:20190618214619).

Affected Platforms:

• Windows 10 64bit.
• Windows 7 64bit.

Steps to Reproduce:

1. Launch Firefox.
2. Access the about:config page.
3. Create the fission.autostart pref and set it to true.
4. Access the following link.
5. Wait a couple of seconds.

Expected Result:

• The website is successfully displayed and Firefox is stable.

Actual Result:

• Firefox Crashes.

I ran into this on resizing cnn.com on Mac

Even just scrolling around cnn.com seemed to cause this.

I can reliably reproduce by just loading reddit.com/r/videos.

This should probably block m4

Bugbug thinks this bug is a regression, but please revert this change in case of error.

Not a regression because it is only happening with fission enabled.

ni'ing farre for helping Kashav with the cause and explanation.

Adding another signature with the same Moz Crash Reason, MOZ_RELEASE_ASSERT(false) (Trying to detach out of process context) .

This could also be because of bug 1555287.

Bug 1555287 has been backed out so let's keep an eye if the signature disappears.

mozilla::dom::ContentParent::RecvDetachBrowsingContext continues to be seen.

https://crash-stats.mozilla.org/report/index/fbc892f5-5d16-4efa-bdec-b8d5b0190625

We also experienced a tab crash with the same signature [@ mozilla::dom::ContentParent::RecvDetachBrowsingContextChildren ] while scrolling the main page of Reddit on Windows 10x64 with the latest FF Nightly. (2019-06-27)

(In reply to Vlad Lucaci, QA (:vlucaci) from comment #12)

https://crash-stats.mozilla.org/report/index/fbc892f5-5d16-4efa-bdec-b8d5b0190625

We also experienced a tab crash with the same signature [@ mozilla::dom::ContentParent::RecvDetachBrowsingContextChildren ] while scrolling the main page of Reddit on Windows 10x64 with the latest FF Nightly. (2019-06-27)

The BuildId in this crash is 20190624213657. RecvDetachBrowsingContextChildren was backed out on the 24th, so you should not see this signature in the latest Nightly (you may still see mozilla::dom::ContentParent::RecvDetachBrowsingContext).

I'm able to reliably reproduce the crash at mozilla::dom::ContentParent::RecvDetachBrowsingContext when just scrolling up and down for 3 secs on cnn.com

https://crash-stats.mozilla.org/report/index/15a58473-0877-4c7f-9a5f-dc2550190704 is the crash report.

This parent process crash should be fixed by bug 1563619. The problem here is that subframe crashes are crashing the parent process, so fixing 1563619 will probably reveal a number of new child process crashes.