pyqt5 segmentation fault on import

Question

Importing Qt from PyQt5 gives a segmentation fault.

$ python
Python 2.7.12 (default, Nov 19 2016, 06:48:10) 
[GCC 5.4.0 20160609] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> from PyQt5 import Qt
[1]    7667 segmentation fault (core dumped)  python

Running using GDB gives some more information.

$ gdb -ex r --args python -c "from PyQt5 import Qt"
...
Starting program: /usr/bin/python -c from\ PyQt5\ import\ Qt
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".

Program received signal SIGSEGV, Segmentation fault.
strlen () at ../sysdeps/x86_64/strlen.S:106
106 ../sysdeps/x86_64/strlen.S: No such file or directory.

EDIT: For versioning reasons, I had to compile PyQt5 from source. Here is the full output from PyQt's configuration script. Below is an abbreviated version.

$ python configure.py --verbose --qmake=/home/jeff/Qt/5.9.2/gcc_64/bin/qmake
Querying qmake about your Qt installation...
Determining the details of your Qt installation...
/home/jeff/Qt/5.9.2/gcc_64/bin/qmake -o cfgtest_QtCore.mk cfgtest_QtCore.pro
Info: creating stash file /home/jeff/Downloads/PyQt5_gpl-5.9/.qmake.stash
make -f cfgtest_QtCore.mk
g++ -c -pipe -O2 -std=gnu++11 -Wall -W -D_REENTRANT -fPIC -DQT_NO_DEBUG -DQT_CORE_LIB -I. -I../../Qt/5.9.2/gcc_64/include -I../../Qt/5.9.2/gcc_64/include/QtCore -I. -I../../Qt/5.9.2/gcc_64/mkspecs/linux-g++ -o cfgtest_QtCore.o config-tests/cfgtest_QtCore.cpp
g++ -Wl,-O1 -Wl,-rpath,/home/jeff/Qt/5.9.2/gcc_64/lib -o cfgtest_QtCore cfgtest_QtCore.o   -L/home/jeff/Qt/5.9.2/gcc_64/lib -lQt5Core -lpthread 
./cfgtest_QtCore cfgtest_QtCore.out
This is the GPL version of PyQt 5.9 (licensed under the GNU General Public
License) for Python 2.7.12 on linux2.

Type 'L' to view the license.
Type 'yes' to accept the terms of the license.
Type 'no' to decline the terms of the license.

Do you accept the terms of the license? yes
Found the license file pyqt-gpl.sip.

Checking to see if the QtGui module should be built...
/home/jeff/Qt/5.9.2/gcc_64/bin/qmake -o cfgtest_QtGui.mk cfgtest_QtGui.pro
make -f cfgtest_QtGui.mk
g++ -c -pipe -O2 -std=gnu++11 -Wall -W -D_REENTRANT -fPIC -DQT_NO_DEBUG -DQT_GUI_LIB -DQT_CORE_LIB -I. -I../../Qt/5.9.2/gcc_64/include -I../../Qt/5.9.2/gcc_64/include/QtGui -I../../Qt/5.9.2/gcc_64/include/QtCore -I. -isystem /usr/include/libdrm -I../../Qt/5.9.2/gcc_64/mkspecs/linux-g++ -o cfgtest_QtGui.o config-tests/cfgtest_QtGui.cpp
g++ -Wl,-O1 -Wl,-rpath,/home/jeff/Qt/5.9.2/gcc_64/lib -o cfgtest_QtGui cfgtest_QtGui.o   -L/home/jeff/Qt/5.9.2/gcc_64/lib -lQt5Gui -lQt5Core -lGL -lpthread 
./cfgtest_QtGui cfgtest_QtGui.out

...

Checking to see if the QtWebKit module should be built...
/home/jeff/Qt/5.9.2/gcc_64/bin/qmake -o cfgtest_QtWebKit.mk cfgtest_QtWebKit.pro
Project ERROR: Unknown module(s) in QT: webkit

Checking to see if the QtWebKitWidgets module should be built...
/home/jeff/Qt/5.9.2/gcc_64/bin/qmake -o cfgtest_QtWebKitWidgets.mk cfgtest_QtWebKitWidgets.pro
Project ERROR: Unknown module(s) in QT: webkitwidgets

...

Checking to see if the QAxContainer module should be built...
/home/jeff/Qt/5.9.2/gcc_64/bin/qmake -o cfgtest_QAxContainer.mk cfgtest_QAxContainer.pro
Project ERROR: Unknown module(s) in QT: axcontainer

...

Checking to see if the QtMacExtras module should be built...
/home/jeff/Qt/5.9.2/gcc_64/bin/qmake -o cfgtest_QtMacExtras.mk cfgtest_QtMacExtras.pro
Project ERROR: Unknown module(s) in QT: macextras

...

Checking to see if the QtWinExtras module should be built...
/home/jeff/Qt/5.9.2/gcc_64/bin/qmake -o cfgtest_QtWinExtras.mk cfgtest_QtWinExtras.pro
Project ERROR: Unknown module(s) in QT: winextras

...

Checking to see if the Enginio module should be built...
/home/jeff/Qt/5.9.2/gcc_64/bin/qmake -o cfgtest_Enginio.mk cfgtest_Enginio.pro
Project ERROR: Unknown module(s) in QT: enginio

...

Checking to see if the QtWebEngine module should be built...
/home/jeff/Qt/5.9.2/gcc_64/bin/qmake -o cfgtest_QtWebEngine.mk cfgtest_QtWebEngine.pro
make -f cfgtest_QtWebEngine.mk
g++ -c -pipe -O2 -std=gnu++11 -Wall -W -D_REENTRANT -fPIC -DQT_NO_DEBUG -DQT_WEBENGINE_LIB -DQT_WEBENGINECORE_LIB -DQT_QUICK_LIB -DQT_GUI_LIB -DQT_WEBCHANNEL_LIB -DQT_QML_LIB -DQT_NETWORK_LIB -DQT_POSITIONING_LIB -DQT_CORE_LIB -I. -I../../Qt/5.9.2/gcc_64/include -I../../Qt/5.9.2/gcc_64/include/QtWebEngine -I../../Qt/5.9.2/gcc_64/include/QtWebEngineCore -I../../Qt/5.9.2/gcc_64/include/QtQuick -I../../Qt/5.9.2/gcc_64/include/QtGui -I../../Qt/5.9.2/gcc_64/include/QtWebChannel -I../../Qt/5.9.2/gcc_64/include/QtQml -I../../Qt/5.9.2/gcc_64/include/QtNetwork -I../../Qt/5.9.2/gcc_64/include/QtPositioning -I../../Qt/5.9.2/gcc_64/include/QtCore -I. -isystem /usr/include/libdrm -I../../Qt/5.9.2/gcc_64/mkspecs/linux-g++ -o cfgtest_QtWebEngine.o cfgtest_QtWebEngine.cpp
cfgtest_QtWebEngine.cpp: In function ‘int main(int, char**)’:
cfgtest_QtWebEngine.cpp:5:17: warning: unused variable ‘v’ [-Wunused-variable]
    const char *v = QTWEBENGINE_VERSION_STR;
                ^
g++ -Wl,-O1 -Wl,-rpath,/home/jeff/Qt/5.9.2/gcc_64/lib -Wl,-rpath-link,/home/jeff/Qt/5.9.2/gcc_64/lib -o cfgtest_QtWebEngine cfgtest_QtWebEngine.o   -L/home/jeff/Qt/5.9.2/gcc_64/lib -lQt5WebEngine -lQt5WebEngineCore -lQt5Quick -lQt5Gui -lQt5WebChannel -lQt5Qml -lQt5Network -lQt5Positioning -lQt5Core -lGL -lpthread 
Checking to see if the dbus support module should be built...
pkg-config --cflags-only-I --libs dbus-1
Qt v5.9.2 is being used.
The qmake executable is /home/jeff/Qt/5.9.2/gcc_64/bin/qmake.
Qt is built as a shared library.
SIP 4.19.3 is being used.
The sip executable is /usr/bin/sip.
These PyQt5 modules will be built: QtCore, QtGui, QtHelp, QtMultimedia,
QtMultimediaWidgets, QtNetwork, QtOpenGL, QtPrintSupport, QtQml, QtQuick,
QtSql, QtSvg, QtTest, QtWidgets, QtXml, QtXmlPatterns, QtDesigner, QtDBus,
_QOpenGLFunctions_2_0, _QOpenGLFunctions_2_1, _QOpenGLFunctions_4_1_Core,
QtSensors, QtSerialPort, QtX11Extras, QtBluetooth, QtPositioning,
QtQuickWidgets, QtWebSockets, QtWebChannel, QtWebEngineWidgets, QtLocation,
QtNfc, QtWebEngineCore, QtWebEngine.
The PyQt5 Python package will be installed in /usr/lib/python2.7/dist-packages.
PyQt5 is being built with generated docstrings.
PyQt5 is being built with 'protected' redefined as 'public'.
The Designer plugin will be installed in
/home/jeff/Qt/5.9.2/gcc_64/plugins/designer.
The qmlscene plugin will be installed in
/home/jeff/Qt/5.9.2/gcc_64/plugins/PyQt5.
The dbus support module will be installed in
/usr/local/lib/python2.7/dist-packages/dbus/mainloop.
The PyQt5 .sip files will be installed in /usr/share/sip/PyQt5.
pyuic5, pyrcc5 and pylupdate5 will be installed in /usr/bin.
The interpreter used by pyuic5 is /usr/bin/python.
Generating the C++ source for the QtCore module...
/usr/bin/sip -w -f -x VendorID -t WS_X11 -t Qt_5_9_2 -x Py_v3 -B Qt_6_0_0 -P -o -c /home/jeff/Downloads/PyQt5_gpl-5.9/QtCore -I sip -I /home/jeff/Downloads/PyQt5_gpl-5.9/sip /home/jeff/Downloads/PyQt5_gpl-5.9/sip/QtCore/QtCoremod.sip
Embedding sip flags...

Generating the .pro file for the QtCore module...
Generating the C++ source for the QtGui module...
/usr/bin/sip -w -f -x VendorID -t WS_X11 -t Qt_5_9_2 -x Py_v3 -B Qt_6_0_0 -P -o -c /home/jeff/Downloads/PyQt5_gpl-5.9/QtGui -I sip -I /home/jeff/Downloads/PyQt5_gpl-5.9/sip /home/jeff/Downloads/PyQt5_gpl-5.9/sip/QtGui/QtGuimod.sip

...

Generating the .pro file for the pyrcc module...
Generating the C++ source for the Qt module...
/usr/bin/sip -w -f -x VendorID -t WS_X11 -t Qt_5_9_2 -x Py_v3 -B Qt_6_0_0 -P -c /home/jeff/Downloads/PyQt5_gpl-5.9/Qt -I sip -I /home/jeff/Downloads/PyQt5_gpl-5.9/sip sip/Qt/Qtmod.sip

Generating the .pro file for the Qt module...
Generating the pylupdate5 wrapper...
Generating the pyrcc5 wrapper...
Generating the pyuic5 wrapper...
Generating the Qt Designer plugin .pro file...
Generating the qmlscene plugin .pro file...
Re-writing
/home/jeff/Downloads/PyQt5_gpl-5.9/examples/quick/tutorials/extending/chapter6-plugins/Charts/qmldir...

Generating the .pro file for the dbus module...
Generating the top-level .pro file...
Making the pylupdate5 wrapper executable...
Making the pyrcc5 wrapper executable...
Making the pyuic5 wrapper executable...
Generating the Makefiles...
/home/jeff/Qt/5.9.2/gcc_64/bin/qmake -recursive PyQt5.pro
Reading /home/jeff/Downloads/PyQt5_gpl-5.9/QtCore/QtCore.pro
Reading /home/jeff/Downloads/PyQt5_gpl-5.9/QtGui/QtGui.pro
Reading /home/jeff/Downloads/PyQt5_gpl-5.9/QtHelp/QtHelp.pro
Reading /home/jeff/Downloads/PyQt5_gpl-5.9/QtMultimedia/QtMultimedia.pro
Reading /home/jeff/Downloads/PyQt5_gpl-5.9/QtMultimediaWidgets/QtMultimediaWidgets.pro
Reading /home/jeff/Downloads/PyQt5_gpl-5.9/QtNetwork/QtNetwork.pro
Reading /home/jeff/Downloads/PyQt5_gpl-5.9/QtOpenGL/QtOpenGL.pro
Reading /home/jeff/Downloads/PyQt5_gpl-5.9/QtPrintSupport/QtPrintSupport.pro
Reading /home/jeff/Downloads/PyQt5_gpl-5.9/QtQml/QtQml.pro
Reading /home/jeff/Downloads/PyQt5_gpl-5.9/QtQuick/QtQuick.pro
Reading /home/jeff/Downloads/PyQt5_gpl-5.9/QtSql/QtSql.pro
Reading /home/jeff/Downloads/PyQt5_gpl-5.9/QtSvg/QtSvg.pro
Reading /home/jeff/Downloads/PyQt5_gpl-5.9/QtTest/QtTest.pro
Reading /home/jeff/Downloads/PyQt5_gpl-5.9/QtWidgets/QtWidgets.pro
Reading /home/jeff/Downloads/PyQt5_gpl-5.9/QtXml/QtXml.pro
Reading /home/jeff/Downloads/PyQt5_gpl-5.9/QtXmlPatterns/QtXmlPatterns.pro
Reading /home/jeff/Downloads/PyQt5_gpl-5.9/QtDesigner/QtDesigner.pro
Reading /home/jeff/Downloads/PyQt5_gpl-5.9/QtDBus/QtDBus.pro
Reading /home/jeff/Downloads/PyQt5_gpl-5.9/_QOpenGLFunctions_2_0/_QOpenGLFunctions_2_0.pro
Reading /home/jeff/Downloads/PyQt5_gpl-5.9/_QOpenGLFunctions_2_1/_QOpenGLFunctions_2_1.pro
Reading /home/jeff/Downloads/PyQt5_gpl-5.9/_QOpenGLFunctions_4_1_Core/_QOpenGLFunctions_4_1_Core.pro
Reading /home/jeff/Downloads/PyQt5_gpl-5.9/QtSensors/QtSensors.pro
Reading /home/jeff/Downloads/PyQt5_gpl-5.9/QtSerialPort/QtSerialPort.pro
Reading /home/jeff/Downloads/PyQt5_gpl-5.9/QtX11Extras/QtX11Extras.pro
Reading /home/jeff/Downloads/PyQt5_gpl-5.9/QtBluetooth/QtBluetooth.pro
Reading /home/jeff/Downloads/PyQt5_gpl-5.9/QtPositioning/QtPositioning.pro
Reading /home/jeff/Downloads/PyQt5_gpl-5.9/QtQuickWidgets/QtQuickWidgets.pro
Reading /home/jeff/Downloads/PyQt5_gpl-5.9/QtWebSockets/QtWebSockets.pro
Reading /home/jeff/Downloads/PyQt5_gpl-5.9/QtWebChannel/QtWebChannel.pro
Reading /home/jeff/Downloads/PyQt5_gpl-5.9/QtWebEngineWidgets/QtWebEngineWidgets.pro
Reading /home/jeff/Downloads/PyQt5_gpl-5.9/QtLocation/QtLocation.pro
Reading /home/jeff/Downloads/PyQt5_gpl-5.9/QtNfc/QtNfc.pro
Reading /home/jeff/Downloads/PyQt5_gpl-5.9/QtWebEngineCore/QtWebEngineCore.pro
Reading /home/jeff/Downloads/PyQt5_gpl-5.9/QtWebEngine/QtWebEngine.pro
Reading /home/jeff/Downloads/PyQt5_gpl-5.9/pylupdate/pylupdate.pro
Reading /home/jeff/Downloads/PyQt5_gpl-5.9/pyrcc/pyrcc.pro
Reading /home/jeff/Downloads/PyQt5_gpl-5.9/Qt/Qt.pro
Reading /home/jeff/Downloads/PyQt5_gpl-5.9/designer/designer.pro
Reading /home/jeff/Downloads/PyQt5_gpl-5.9/qmlscene/qmlscene.pro
Reading /home/jeff/Downloads/PyQt5_gpl-5.9/dbus/dbus.pro

PyQt should ignore Qt modules that it doesn't recognize for compatibility across all Qt 5.x versions, so the "unknown module" bits aren't too concerning.

I'm using:

• Ubuntu 16.04
• Python 2.7.12
• Qt 5.9.2
• SIP 4.19.3 (Compiled from source)
• PyQt 5.9 (Compiled from source)

Answer 1

I had the very same issue on a different setup (Slackware), which caused Openshot to crash silently on startup.

The reason was that an upgrade installed packages from different sources (slackonly and alienbob).

Searching for packages named with "qt5" and "Qt5" allowed me to identify wrong packages and replace them with relevant versions, which solved the issue.

Answer 2

An older version of SIP was present on the machine and was being imported instead of the new one, built from source, used to build PyQt. Removing the old version of SIP fixes the issue.

Before

$ python
>>> import sip
>>> print sip.SIP_VERSION_STR
4.17

After removing the old version with sudo apt remove python-sip

$ python
>>> import sip
>>> print sip.SIP_VERSION_STR
4.19.3
>>> from PyQt5 import Qt    # Does not segfault