[SOLVED] RRD4J no charts

This is about switching the chart period - I don’t think it is related to my issue.

I’m quite sure that I did it with switches in some of my older setups. The goal was to monitor the behavior of a presence simulation which switches lights at random …
I’ll look for the backup on one of the old SD cards.

Unfortunately not - no charts at all.
Only error messages 3 times:
[WARN ] [thome.ui.internal.chart.ChartServlet] - Chart generation failed: null

Could it be that the database is somehow defective? Is it possible to reset/delete it?

The persistence viewer delivers the following output:
http://openhabianpi:8080/static/PersistenceViewer/?rrd4j

There is no EG_bad_x_tp1_energyusage at all …