Space not allowed for username despite Import mode disabled

We have a custom database for our Auth0 application.

We tried to send a password change ticket to Auth0. It responded with:

"DB Custom script (get_user): invalid fields. Username can only contain alphanumeric characters and the following characters: '_', '+', '-', '.', '!', '#', '$', ''', '^', '', '~' and '@'."

Per this Knowledge Base article:

When using custom databases the behaviour is slightly different depending on whether import mode enabled.

If disabled:

The rules for allowed characters does not apply i.e. you can use any characters for username and it will be accepted.

When I look at our DB config:

  • “Import Users to Auth0” Is turned OFF. I presume this means import mode is disabled.

  • Under Attributes → Username Configuration: “Use Username as Identifier” is ON.

Should we expect that error to NOT happen, since import mode is off?