This bug was filed from the Socorro interface and is report bp-d6e71090-ea55-42e0-bb39-6e0530180825. ============================================================= Top 10 frames of crashing thread: 0 xul.dll static void std::panicking::rust_panic_with_hook src/libstd/panicking.rs:521 1 xul.dll static void std::panicking::continue_panic_fmt src/libstd/panicking.rs:426 2 xul.dll static void std::panicking::rust_begin_panic src/libstd/panicking.rs:337 3 xul.dll static void core::panicking::panic_fmt src/libcore/panicking.rs:92 4 xul.dll static void core::option::expect_failed src/libcore/option.rs:960 5 xul.dll static union core::option::Option<euclid::transform3d::TypedTransform3D<f32, webrender_api::units::LayoutPixel, webrender_api::units::LayoutPixel>> webrender::clip_scroll_tree::ClipScrollTree::get_relative_transform gfx/webrender/src/clip_scroll_tree.rs:164 6 xul.dll static void webrender::prim_store::PrimitiveStore::prepare_prim_runs gfx/webrender/src/prim_store.rs:1814 7 xul.dll static union core::option::Option<euclid::rect::TypedRect<f32, webrender_api::units::LayoutPixel>> webrender::prim_store::PrimitiveStore::prepare_prim_for_render gfx/webrender/src/prim_store.rs:1562 8 xul.dll static void webrender::prim_store::PrimitiveStore::prepare_prim_runs gfx/webrender/src/prim_store.rs:1819 9 xul.dll static union core::option::Option<euclid::rect::TypedRect<f32, webrender_api::units::LayoutPixel>> webrender::prim_store::PrimitiveStore::prepare_prim_for_render gfx/webrender/src/prim_store.rs:1562 ============================================================= There are 2 crashes (from 1 installation) in nightly 63 with buildid 20180824222409. In analyzing the backtrace, the regression may have been introduced by patch [1] to fix bug 1485691. [1] https://hg.mozilla.org/mozilla-central/rev?node=4a57ba156ecf

Marking fix-optional for 64. We could still take a patch for 65, and if it's verified and doesn't seem risky, could still take fixes for 64 as well.

This will most likely be fixed by https://github.com/servo/webrender/pull/3331 when it lands in Gecko.

Should be fixed now, reopen if it comes back