vnstat2: Importing DBs from vnstat1 fails

[BlessDeix92]

OpenWrt version

r23809 OpenWrt release

23.05.3

I tried to upgrade an openwrt system from vnstat v1 to v2. Unfortunately, none of the database could be upgraded, so vnstat loses all of the historical data.

I am not the only one with this problem: https://forum.openwrt.org/t/solved-vnstat-2-import-old-database/148981

However, I have no idea what the above person was doing, since those import/export arguments don't exist.

When running "./vnstatd -D -n" manually, I get the following errors:

        Importing data from legacy database "eth0.2".
        db: Database read failed for file "/srv/vnstat/eth0.2".
        Error: Database load failed even when using backup (No such file or directory). Aborting.

There is nothing wrong with the input DB files. They work fine on a v1 system. There is no permission or other strange problem here.