This bug was filed from the Socorro interface and is report bp-33e62393-d862-45a1-9d1f-36add0180815. ============================================================= Seen while looking at nightly crash stats - crashes started using 20180814220344: https://bit.ly/2Mp9LrS. 10 crashes/5 installs so far. Possible regression range based on Build ID: https://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=bf79440c1376b1e1114ba653917e1577d7b1007b&tochange=fa2f3d22c1564e6318725061c390834729a4df66 Top 10 frames of crashing thread: 0 xul.dll NS_ABORT_OOM xpcom/base/nsDebugImpl.cpp:624 1 xul.dll nsresult mozilla::dom::XMLHttpRequestMainThread::AppendToResponseText dom/xhr/XMLHttpRequestMainThread.cpp:538 2 xul.dll static nsresult mozilla::dom::XMLHttpRequestMainThread::StreamReaderFunc dom/xhr/XMLHttpRequestMainThread.cpp:1602 3 xul.dll nsStringInputStream::ReadSegments xpcom/io/nsStringStream.cpp:270 4 xul.dll mozilla::dom::XMLHttpRequestMainThread::OnDataAvailable dom/xhr/XMLHttpRequestMainThread.cpp:1787 5 xul.dll nsCORSListenerProxy::OnDataAvailable netwerk/protocol/http/nsCORSListenerProxy.cpp:678 6 xul.dll nsresult mozilla::net::nsHTTPCompressConv::do_OnDataAvailable netwerk/streamconv/converters/nsHTTPCompressConv.cpp:528 7 xul.dll static nsresult mozilla::net::nsHTTPCompressConv::BrotliHandler netwerk/streamconv/converters/nsHTTPCompressConv.cpp:234 8 xul.dll nsStringInputStream::ReadSegments xpcom/io/nsStringStream.cpp:270 9 xul.dll mozilla::net::nsHTTPCompressConv::OnDataAvailable netwerk/streamconv/converters/nsHTTPCompressConv.cpp:474 =============================================================

Duping to the later filed bug since there is more information there.