Help: ICP Gateway returns Error 400 Unknown Domain

[rbirkner]

I have posted some more insights/details in this thread. Have a look at these replies in particular:

Custom Domain Re-registration?

Hey @WebTreeSoftwareSolut and @Cris.MntYetti, we do experience some flakiness (especially with apex domains). Often the cause is that the domain is registered with Cloudflare and there is some misconfiguration. When you use Cloudflare, you need to make sure that you have disable edge certificates as it can interfere with the custom domains service. You can disable it the following way: Go to your domain in the cloudflare panel, then go to “SSL/TLS” → “Edge Certificates”, scroll all the way dow…

Custom Domain Re-registration?

The issue with these Edge Certificates by Cloudflare is that if enabled, Cloudflare also obtains certificates for the domain. To do so, Cloudflare also uses the ACME DNS-01 challenge just as our custom domains service does. We have observed now multiple times that sometimes Cloudflare fails to clean up the TXT records it sets and these then interfere with our custom domains service as Let’s Encrypt does not follow the redirect (CNAME to _acme-challenge.your-domain.com.icp2.io) but just checks th…