What it means
use_x_forwarded_for is on, but the request came through a proxy whose address is not in trusted_proxies, so Home Assistant rejects it.
Why it happens
- The proxy runs in Docker and its address changes or is not the one you listed (Docker networks are 172.16.0.0/12).
- A second proxy in the chain (for example Cloudflare in front of nginx) is not listed.
How to fix it
- Add the exact address from the message, or the Docker network (172.16.0.0/12), to trusted_proxies.
- With several proxies list every one between the client and Home Assistant.
- Restart Home Assistant after the change.
Useful tools
/home-assistant-remote-access/
Other Home Assistant errors
- A request from a reverse proxy was received from 172.30.33.0, but your HTTP integration is
- Login attempt or request with invalid authentication from 192.168.1.50 (192.168.1.50). Req
- Invalid config for 'automation' at automations.yaml, line 3: required key 'triggers' not p
- Template variable warning: 'dict object' has no attribute 'to_state' when rendering '{{ tr
- Setup failed for 'hacs': Integration not found.