Just ran into the following trying to do a manual update with mender install. Even deleting the Mender data and restarting mender-client did not fix the issue.
ERRO[0000] Failed to open DB environment: mdb_env_open: no such file or directory
ERRO[0000] failed to initialize DB store
It turns out that it is because the data is stored in /data/mender, which I pass to the daemon in the service file. I don’t see a way to configure this in /etc/mender/mender.conf. It would be really nice, rather than remembering to pass --data every time.