Cannot "Ad User" Home Assistant OS

Configuration
1

core-2021.3.2
supervisor-2021.03.4
Home Assistant OS 5.12

I’m migrating from a Raspberry Pi 4 configuration to a Lenovo M90n, which is like a NUC. I’m restoring my entire configuration by hand (rather than restore via snapshop). I’m now trying to

Configuration -> Users -> ADD USER

and no matter what I try I get an “Unknonw error” in red at the top of the window. I’m stumped.

2

Answering my own question, although I don’t understand the exact whys.

I had restored this section in my configuration.yaml:

homeassistant:
  auth_providers:
    - type: trusted_networks
      trusted_networks:
        - 192.168.1.0/24

I could not create a new user until I changed it to this:

homeassistant:
  auth_providers:
    - type: homeassistant
    - type: trusted_networks
      trusted_networks:
        - 192.168.1.0/24

When I built my RPi 4 configuration I added the user I needed before I turned on trusted networks. Thus I didn’t see this problem previously.