Arch Linux

nigeil

Member

Registered: 2014-06-13

Posts: 8

Undefined symbol error when importing PyQt5.Core

If I try to import (in python) PyQt5.QtCore, issues arise:

 
ImportError                               Traceback (most recent call last)
<ipython-input-1-2bb10a0eb39a> in <module>()
----> 1 import PyQt5.QtCore

ImportError: /usr/lib/python3.4/site-packages/PyQt5/QtCore.so: undefined symbol: _ZTI13QFileSelector

Unwrapping that symbol with c++filt, I get:

 typeinfo for QFileSelector 

This issue pops up when compiling sonic-pi-git. It also prevents the launch of applications like leo that import PyQt5.Core.

This is only an issue on one of my systems, a laptop with an Intel i7 (Haswell) processor. My AMD-based desktop does not have this issue.

I think it's probably a poorly installed library, but which one it is and how I fix it is a mystery to me. Any thoughts are appreciated, more info can be provided on request. Thank you for your time.

Scimmia

Fellow

Registered: 2012-09-01

Posts: 13,729

Re: Undefined symbol error when importing PyQt5.Core

Is that one system fully up to date?

Works fine here on a Haswell I7 system.

nigeil

Member

Registered: 2014-06-13

Posts: 8

Re: Undefined symbol error when importing PyQt5.Core

Good first thing to check, but yes I updated it this morning; it has been an issue for some time now, 2 months at least. It also is not a problem on a clean-install of Antergos on a virtual machine. I suppose I could do a clean install again, but I'd like that to be a last resort, as it's not mission-critical yet.

WorMzy

Administrator

From: Scotland

Registered: 2010-06-16

Posts: 13,718

Website

Re: Undefined symbol error when importing PyQt5.Core

Just to be sure: are you using Arch or Antergos? An up-to-date Antergos system != an up-to-date Arch system.

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nigeil

Member

Registered: 2014-06-13

Posts: 8

Re: Undefined symbol error when importing PyQt5.Core

Again, good clarification. I am running an ARCH system. Everything is up-to-date and no other issues have been troubling me as of late.

I maintain the package sonic-pi-git in the AUR and set that Antergos VM up once I saw that I was having issues building QT applications on my laptop. Not really the Arch way to deal with that problem, but it suffices for now.

Scimmia

Fellow

Registered: 2012-09-01

Posts: 13,729

Re: Undefined symbol error when importing PyQt5.Core

I would run pacman -Qkk on your system, then. See if it reports problems with any library files (size mismatch, etc).

nigeil

Member

Registered: 2014-06-13

Posts: 8

Re: Undefined symbol error when importing PyQt5.Core

I would run pacman -Qkk on your system, then. See if it reports problems with any library files (size mismatch, etc).

A good idea. A few packages reported errors, but none seem relevant at all. Regardless I've reinstalled the broken packages and still have the same issue. *deep sigh*

Scimmia

Fellow

Registered: 2012-09-01

Posts: 13,729

Re: Undefined symbol error when importing PyQt5.Core

Any chance you have old libs hanging around that were installed outside of pacman?

What about optional deps? I have all of the qt5-* optional deps installed except qt5-serialport.

nigeil

Member

Registered: 2014-06-13

Posts: 8

Re: Undefined symbol error when importing PyQt5.Core

Any chance you have old libs hanging around that were installed outside of pacman?

What about optional deps? I have all of the qt5-* optional deps installed except qt5-serialport.

It's possible that I do have an extra one hanging on there. I've got all of the optional dependencies of qt5-base installed, and I might have haphazardly installed a qt5 package from the AUR when I was building sonic-pi.

What I'm going to do is get a list of the qt5-* packages installed locally and check them against my known working system(s), to see what differences there are in version numbers and such. I'll report back.

nigeil

Member

Registered: 2014-06-13

Posts: 8

Re: Undefined symbol error when importing PyQt5.Core

I've investigated further and found that I am actually a liar; I am running into the same issue on my desktop Arch machine. I get the same error when attempting to import PyQt5.QtCore in python as I do on my laptop:

import PyQt5.QtCore
ImportError: /usr/lib/python3.4/site-packages/PyQt5/QtCore.so: undefined symbol: _ZTI13QFileSelector

Importing PyQt4.QtCore is not an issue, so it seems the PyQt4 libraries are fine. I've reinstalled (cleanly) both sets of libraries, to no avail.

Importing other things from PyQt5, such as PyQt5.Qt, does not seem to be a problem. I've not run extensive tests because I'm not really familiar with that library; but it seems that the issue is contained to the PyQt5/QtCore.so file.

Perhaps the PyQt5 library that Arch is shipping is not fully functional? Maybe I'll try grabbing the sources and installing them myself.

nigeil

Member

Registered: 2014-06-13

Posts: 8

Re: Undefined symbol error when importing PyQt5.Core

Well I've got good news and bad news it seems.

Bad: installing the latest development snapshot of PyQt5 (PyQt-gpl-5.5-snapshot-f6bfd44ba749) from their website did not solve the problem. The same error occurs on trying to import PyQt5.QtCore. This issue is still non-existant on my Antergos VM with the official packages, which have the same version numbers as those in the Arch repos. 

Good: removing the python2-pyqt5 package solves my issue with launching the program Leo, so it seems the library import and Leo issues might be unrelated. Still need this package as a dependency for other programs though...

I'm kind of stumped. Is the next best step just removing packages until I've found the one that's breaking this part of the library, or seeking some help upstream? And is anyone else running into this issue as well, or is it really just me?

duanev

Member

Registered: 2012-02-26

Posts: 14

Re: Undefined symbol error when importing PyQt5.Core

nigeil, you are not the only one:

$ python
Python 3.4.3 (default, Mar 25 2015, 17:13:50) 
[GCC 4.9.2 20150304 (prerelease)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> from PyQt5 import QtCore
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: /usr/lib/python3.4/site-packages/PyQt5/QtCore.so: undefined symbol: _ZN19QItemSelectionModel8setModelEP18QAbstractItemModel
>>> 

however, refreshing the qt5 packages I have installed solved it:

# pacman -S qt5-base qt5-declarative qt5-location qt5-script qt5-sensors qt5-svg qt5-tools  qt5-translations qt5-webchannel qt5-webkit qt5-x11extras qt5-xmlpatterns

Last edited by duanev (2015-09-25 17:35:41)

bijanbina

Member

From: Tehran

Registered: 2014-07-13

Posts: 20

Website

Re: Undefined symbol error when importing PyQt5.Core

nigeil, you are not the only one:

$ python
Python 3.4.3 (default, Mar 25 2015, 17:13:50) 
[GCC 4.9.2 20150304 (prerelease)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> from PyQt5 import QtCore
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: /usr/lib/python3.4/site-packages/PyQt5/QtCore.so: undefined symbol: _ZN19QItemSelectionModel8setModelEP18QAbstractItemModel
>>> 

however, refreshing the qt5 packages I have installed solved it:

# pacman -S qt5-base qt5-declarative qt5-location qt5-script qt5-sensors qt5-svg qt5-tools  qt5-translations qt5-webchannel qt5-webkit qt5-x11extras qt5-xmlpatterns

reinstalling Works!
TanQ