QGIS » QGIS Application

To reproduce¶

1. Download and unpack https://github.com/geometalab/osmaxx/blob/v2.5.0/osmaxx/core/static/osmaxx/example_data/rapperswil_wgs-84_2016-10-05_gpkg_full-detail.zip
2. from the extracted folder, open symbology/QGIS/OSMaxx.qgs in QGIS
3. In the "Layer Styling" panel, choose a layer with "Single symbol" symbology, e.g. transport_l (a linestring layer) or address_p (a point layer)
4. Change that layer to a categorized layer with the drop-down menu just below the Layer Styling layer selection drop-down.
   Note that the previous single symbol is not being converted to a category. In fact, the categories list is empty.
   Leave it empty, don't add any categories, i.e. click neither the "Classify" nor the "+" button.
5. Save the project
6. Close QGIS
7. Open the project again in QGIS
8. In the "Layer Styling" panel, choose the layer you modified before.

Expected¶

• The symbology of the layer is still "Categorized"
  • still with empty categories list and
  • categories can be added now manually (button "+") or automatically (button "Classify") as if the project hadn't been closed after step 4 above
• or QGIS should have populated the list with a default category in step 4 above (best based on previous single symbol)
• and/or QGIS shouldn't have allowed me to save the project with a categorized symbol without categories

Observed¶

• The selected value of the drop-down menu just below the Layer Styling layer selection drop-down is now blank. (If you open the drop down menu, all expected values are still offered.)
• In the area where the symbol(s) can usually be configured (below that second drop down menu) it just says "This renderer doesn't implement a graphical interface."
• After step 5 above, the changed <renderer-v2> can be seen in the sourcecode (XML) of the project file, indeed without any <categories> sub-element.
• If after step 8 above, the project is saved again, the <renderer-v2> element will be gone from the XML
• After step 8, attempting to change the symbol type from blank to "Categorized" using the drop-down menu sometimes lets QGIS hang, sometimes closes it immediately, but never seems to succeed.