Custom Domain (CNAME) with Nabu Casa – ACME Validation Fails / Still Nabu Casa Certificate | Home Assistant | Page 1

cunning pulsar Aug 1, 2025, 10:52 AM

#

Hey everyone, I'm currently struggling to set up my own domain with Nabu Casa for Home Assistant.

I've added the required CNAME for _acme-challenge.smarthome.mydomain.cloud, pointing to the domain provided by Nabu Casa (_acme-challenge.***.ui.nabu.casa).
DNS has fully propagated (verified via dig and online checkers – all servers return the correct TXT record).

Still, the ACME validation fails on Nabu Casa's side, and the certificate is still issued for the default *.ui.nabu.casa domain — not my custom domain.

When I access https://smarthome.mydomain.cloud, I get ERR_CONNECTION_CLOSED.

I already tried:

Disabling and re-enabling Remote Access
Temporarily changing the domain in Nabu Casa to trigger a new challenge
Restarting Home Assistant
Waiting over 30 minutes for propagation

Is there a way to force Nabu Casa to revalidate or clear its ACME/DNS cache?

Thanks in advance for any help!

plain spade Aug 1, 2025, 12:39 PM

#

Technically it can take 48 hrs. It probably won't take that long but you might need to wait for longer. Have you checked again since submitting this?

swift kite Aug 1, 2025, 1:29 PM

#

There is no cache, one thing that also can do this is using cloudflare with proxy enabled for it, it needs to be disabled.

quick root Aug 1, 2025, 3:42 PM

#

Having a similiar problem. I registered a domain, added the CNAME records, and they won't validate. Do I need to wait 48 hours or something? If so, that information would be very helpful to put in the setup instructions for adding a custom domain, as I imagine it's a common problem.

plain spade Aug 1, 2025, 3:52 PM

#

quick root Having a similiar problem. I registered a domain, added the CNAME records, and t...

if neither entry validates then you have another issue

quick root Aug 1, 2025, 3:54 PM

#

I just registered the domain, added both hosts and values as CNAME records and neither will validate. Any ideas what I could have done wrong? Using namecheap for the domain.

plain spade Aug 1, 2025, 3:55 PM

#

Do you have simply "home" or the equivalent as the CNAME entered? or is it "home.yourdomain.com" ?

quick root Aug 1, 2025, 3:56 PM

#

home.mydomain.casa

plain spade Aug 1, 2025, 3:56 PM

#

Typically you don't need the full domain but it depends on how namecheap handles it. each provider is different

#

Same for the acme challenge entry

#

Try dropping the full domain

quick root Aug 1, 2025, 4:02 PM

#

Dropping the full domain from the dns entry or the Nabu Casa custom domain card?

quick root Aug 1, 2025, 4:19 PM

#

I used "home" and "_acme-challenge.home" in namecheap as the hosts and the records still won't validate.

#

Just validated. Must have been a propagation thing.

glacial flint Dec 18, 2025, 5:17 AM

#

I'm more or less running into a similar problem as the previous person, however my "home" cname validates just fine, however my acme-challenge domain name/cname fails.

#

I can see the domains fine via https://mxtoolbox.com/SuperTool.aspx

#