Stack trace on starting ChimeraX in Linux

[Tristan Croll]

Looks like a particularly nasty PyQt bug, similar to that discussed at ​https://github.com/qutebrowser/qutebrowser/issues/3662 (reverting from 5.10.1 back to 5.10.0 fixed it for them). Using the latest nightly build, when I run ChimeraX from Linux (Fedora 24) it crashes back to the shell. Running in gdb:

Detaching after fork from child process 3727.
Detaching after fork from child process 3728.
Could not find QtWebEngineProcess
[3705:3705:0325/183757.688666:FATAL:zygote_host_impl_linux.cc(182)] Check failed: ReceiveFixedMessage(fds[0], kZygoteBootMessage, sizeof(kZygoteBootMessage), &boot_pid). 

Thread 1 "ChimeraX" received signal SIGABRT, Aborted.
0x00007ffff6c65765 in raise () from /lib64/libc.so.6
Missing separate debuginfos, use: dnf debuginfo-install cairo-1.14.6-2.fc24.x86_64 cairo-gobject-1.14.6-2.fc24.x86_64 dbus-libs-1.11.8-1.fc24.x86_64 expat-2.1.1-2.fc24.x86_64 gnutls-3.4.16-1.fc24.x86_64 gtk3-3.20.9-1.fc24.x86_64 gvfs-client-1.28.3-1.fc24.x86_64 libgcrypt-1.6.6-1.fc24.x86_64 libpng-1.6.26-1.fc24.x86_64 libtool-ltdl-2.4.6-12.fc24.x86_64 libuuid-2.28.2-1.fc24.x86_64 lz4-1.7.3-1.fc24.x86_64 nspr-4.13.1-1.fc24.x86_64 nss-3.27.0-1.2.fc24.x86_64 nss-softokn-freebl-3.27.0-1.0.fc24.x86_64 nss-util-3.27.0-1.0.fc24.x86_64 pcre-8.39-6.fc24.x86_64 systemd-libs-229-16.fc24.x86_64
(gdb) bt


#0  0x00007ffff6c65765 in raise () from /lib64/libc.so.6
#1  0x00007ffff6c6736a in abort () from /lib64/libc.so.6
#2  0x00007fffc9e04dc5 in ?? () from /home/tic20/apps/chimerax/lib/python3.6/site-packages/PyQt5/Qt/lib/libQt5WebEngineCore.so.5
#3  0x00007fffc9e1b1ed in ?? () from /home/tic20/apps/chimerax/lib/python3.6/site-packages/PyQt5/Qt/lib/libQt5WebEngineCore.so.5
#4  0x00007fffc945dfc3 in ?? () from /home/tic20/apps/chimerax/lib/python3.6/site-packages/PyQt5/Qt/lib/libQt5WebEngineCore.so.5
#5  0x00007fffc945cc3b in ?? () from /home/tic20/apps/chimerax/lib/python3.6/site-packages/PyQt5/Qt/lib/libQt5WebEngineCore.so.5
#6  0x00007fffc945d219 in ?? () from /home/tic20/apps/chimerax/lib/python3.6/site-packages/PyQt5/Qt/lib/libQt5WebEngineCore.so.5
#7  0x00007fffc90a093a in ?? () from /home/tic20/apps/chimerax/lib/python3.6/site-packages/PyQt5/Qt/lib/libQt5WebEngineCore.so.5
#8  0x00007fffc90a5e76 in ?? () from /home/tic20/apps/chimerax/lib/python3.6/site-packages/PyQt5/Qt/lib/libQt5WebEngineCore.so.5
#9  0x00007fffc8bc3600 in ?? () from /home/tic20/apps/chimerax/lib/python3.6/site-packages/PyQt5/Qt/lib/libQt5WebEngineCore.so.5
#10 0x00007fffc8bc4b25 in ?? () from /home/tic20/apps/chimerax/lib/python3.6/site-packages/PyQt5/Qt/lib/libQt5WebEngineCore.so.5
#11 0x00007fffc8b58e85 in QtWebEngineCore::BrowserContextAdapter::BrowserContextAdapter(bool) ()
   from /home/tic20/apps/chimerax/lib/python3.6/site-packages/PyQt5/Qt/lib/libQt5WebEngineCore.so.5
#12 0x00007fffceb0d4aa in QWebEngineProfile::QWebEngineProfile(QObject*) () from /home/tic20/apps/chimerax/lib/python3.6/site-packages/PyQt5/Qt/lib/libQt5WebEngineWidgets.so.5
#13 0x00007fffced47009 in sipQWebEngineProfile::sipQWebEngineProfile(QObject*) () from /home/tic20/apps/chimerax/lib/python3.6/site-packages/PyQt5/QtWebEngineWidgets.so
#14 0x00007fffced471ea in init_type_QWebEngineProfile () from /home/tic20/apps/chimerax/lib/python3.6/site-packages/PyQt5/QtWebEngineWidgets.so
#15 0x00007fffcfb12a74 in sipSimpleWrapper_init () from /home/tic20/apps/chimerax/lib/python3.6/site-packages/sip.so
#16 0x00007ffff797fce3 in type_call (type=<optimized out>, type@entry=0x1207038, args=args@entry=0x7fff9b99b5c0, kwds=kwds@entry=0x0) at Objects/typeobject.c:915
#17 0x00007ffff790e75b in _PyObject_FastCallDict (func=0x1207038, args=<optimized out>, nargs=<optimized out>, kwargs=0x0) at Objects/abstract.c:2331

[tic20@…]

It might be a good idea to provide the last few nightly builds on the 
website, to provide a reasonably up-to-date fallback in situations like 
this?

On 2018-03-25 12:09, ChimeraX wrote:

[Tristan Croll]

Downgrading using the PyQt 5.9 wheel from ​https://pypi.python.org/pypi/PyQt5/5.9 has me up and running again for now.

[Greg Couch]

Reverted to PyQt 5.9.2 with Qt 5.9.3. This bug is may be ​https://bugreports.qt.io/browse/QTBUG-66346 which is in Qt 5.9.4 and Qt 5.10.1 (and fixed in 5.9.5 and 5.11.0). So don't update PyQt 5.9.2 with Qt 5.9.4.

[Greg Couch]

Qt 5.9.5 is planned to be released in late March, i.e, this week. 5.11 isn't due until the end of May. There will be no 5.10.2.