Ah, sorry, I confused it! I exported the wrong database at first and so got a wrong impression, what had happened. If you export without start parameter, it exports the entire database but my following import-trial stopped with errors. So I got the impression, there were errors in the database before 2020, and my next trial was to start around 2023 (you have to compute seconds since 1970 up to 2023 ;-), and it reads like “?export&start=1639872000&componentType=VEVENT”. And so it worked: my calendar entries now start somewhere around 2023.
16.11.2025 14:34:58 MichaIng via DietPi Community Forum forum@dietpi.com: