That couldn’t be done in this case. The instance went from a server where the data directory was on the same volume to a new server with an attached volume.

The problem was that the directory paths are hardcoded (or can be) in two tables, oc_storages and oc_accounts. In my case the problem was only in oc_accounts. I ran this MySQL command to update the hardcoded paths:

update oc_accounts set home = replace(home, "/var/www/data", "/data/owncloud-data") where home like "/var/www/data%";

Problem resolved.

Thanks!