The selected weather station provides weather data with an offset of a few days. Please try with a date (range) a few days in the past (e.g. May 1st).

Thanks for reporting the issue. I will implement some error handling, so that we get a more meaningful error message here.

so I have now updated the plugin to the latest version.
I can retrieve data but only those that are at least 5 days in the past. Is that the way it should be?
if I set the range to 2 days the same error occurs again

The problem is that actual observation data is coming in with an offset of a few days. Therefore, Meteostat uses model data as a substitute for recent days. I don't know if @Kkoile implemented an option for including model data in the Grafana plugin, but it should be straight forward using the model URL parameter: https://dev.meteostat.net/api/stations/hourly.html

Otherwise, I might be able to implement it myself in the upcoming months.