Description:
I have a script that runs in LibreOffice Calc that uses matplotlib.pyplot.
It used to work on a daily basis, but I ran it yesterday, (after a gap of maybe 2 months) and it crashed libreoffice.

Through trial and error I narrowed down the last statement run before the crash to  "import matplotlib.pyplot as plt".  When I removed the statement, the script ran without a crash.

I moved the "import matplotlib.pyplot as plt" line down to after the logging started, and this message came out in the log before the crash occurred:  "Loaded backend qt5agg version unknown."  QT5Agg is a "Backend" for pyplot, i.e., it provides lower-level graphics support for the drawing of the chart images.

If I put this in a python script outside of the libreoffice environment (for example, in a jupyter notebook, or a standalone python script), it doesn't crash.

I'm wondering whether LO cannot access the backend QT5Agg, and that's why this crash is happening.

As I say, this used to work fine every time, and after no changes to the script it crashes Libreoffice, this would have occurred over perhaps the last 2 months.  I've been keeping my software up-to-date.

Python : 3.6.8
Matplotib : 3.1.1
Kubuntu 18.04
KDE: 5.12.9
QT : 5.9.5



Steps to Reproduce:
1.  Create python script with the following lines of code:  (I'm assuming that it would be necessary to match the OS, LO version, etc.)  This is a simplified script that I hope will suffice for bug reporting purposes)

import matplotlib
import matplotlib.pyplot as plt

def ThisBreaksinLO():
    pass

2.  Open an empty Calc spreadsheet and run the script
3.  It will cause LO to crash

Actual Results:
LibreOffice crashed

Expected Results:
The script will run without crashing LibreOffice.  The script does not do anything but load the modules.


Reproducible: Always


User Profile Reset: No



Additional Info:
Version: 6.0.7.3
Build ID: 1:6.0.7-0ubuntu0.18.04.10
CPU threads: 4; OS: Linux 4.15; UI render: default; VCL: kde4; 
Locale: en-CA (en_CA.UTF-8); Calc: group