TUFLOW Viewer Matplotlib Font Error

This page describes how to fix TUFLOW Viewer if you get the following error (or similar). Unfortunately this is a bug with the plotting library TUFLOW Viewer uses (matplotlib) and is due to an issue with its cached data.

ValueError: Failed to find font DejaVu Sans:style=normal:variant=normal:weight=normal:stretch=normal:size=10.0, and fallback to the default font was disabled

To fix this issue, the matplotlib cache data will need to be deleted. The steps below describe how to do this:

1. Open QGIS
2. Open the Python interpreter

   

3. In the python interpreter type the following commands:

   import matplotlib
   print(matplotlib.get_cachedir())
   

   

4. This will print the matplotlib cache directory
5. In this directory, delete the fontlist-v330.json file

   

6. Try opening TUFLOW Viewer (you should not need to restart QGIS, however if it still doesn't work then restarting QGIS will be worth trying)