User Import Fails with Error: 'Custom Database Connections Without Import Mode are not Allowed.'

Problem statement

When attempting to import users for a custom database connection, an error occurs stating that ‘Custom Database Connections without import mode are not allowed.’ Why does this error occur?

Solution

This error is occurring because the Bulk User Import is intended to have Auth0 become the new source of truth for these users, and if you are using a custom database with import mode off, the source of truth for all users in the connection is going to still be the external database. You will not be able to import these user profiles to become visible in the Dashboard unless you intend to have Auth0 become the source of truth for these users by turning Import Mode on.