database is locked

[mowgli]

I use histdb as user and as root. Unfortunately, as root I often get the following error:

Error: stepping, database is locked (5)
History database /root/.histdb/zsh-history.db is using an older schema () and will be updated to version 2.
There is no migration script from version  to 2.

I also get that error some times as user but really seldom. As root it is common to get that error with the first command run in a new shell.