I just hit this as well in my first attempt to install nextcloud, using occ on a VPS running ubuntu 18.04, following the most vanilla instructions. It’s unfortunate to have my first encounter with nextcloud include:
- the documentation is wrong, as it never prompts for a password
- fails with an error meaningless to a non-database-admin, the workarounds discussed here presuppose prior facility with a great deal of irrelevant mysql/mariadb arcana
- and the issue was identified in 2017 and bumped in november 2018