Error 1023 is similar to error 1018 — Cloudflare received a request for a hostname that does not match any active zone. The difference is typically the context in which the error is triggered. Error 1023 commonly appears when the Cloudflare zone exists but the specific subdomain or hostname requested does not have any DNS records, or when a CNAME chain leads to a Cloudflare zone that has been deactivated.
The domain is active on Cloudflare, but there is no A, AAAA, or CNAME record for the specific subdomain being accessed.
The Cloudflare zone exists but has been paused by the account owner, or nameserver verification has lapsed.
A CNAME record chains through multiple hostnames, one of which points to a Cloudflare zone that no longer exists.
Verify that a DNS record exists for the exact hostname returning the error (including the subdomain).
Check DNS RecordsLog into the Cloudflare dashboard and confirm the domain shows as Active, not Paused or Pending.
If the subdomain is missing, add an A or CNAME record in Cloudflare's DNS settings pointing to the correct origin.