Let’s Encrypt ACME 403 / Unauthorized Error via Safeline

Hello Safeline Team,

We are receiving the following error while trying to issue a Let’s Encrypt certificate, and we would like your help to understand the root cause.

Error message:

error: one or more domains had a problem:
[.com.tr]
acme: error: 403 :: urn:ietf:params:acme:error:unauthorized ::
XX.XX.XX.XXX: Invalid response from
http://.com.tr/.well-known/acme-challenge/<challenge_token> : 503

From what we observe, the ACME HTTP-01 challenge request reaches the server but returns HTTP 503, which causes Let’s Encrypt to mark the validation as unauthorized (403). At the moment, certificate issuance fails consistently via Let’s Encrypt, and we would like to understand what is not working on the Safeline side.

Looking forward to your guidance.

Best regards,

Could you please check whether the WAF's detection and forwarding are currently functioning normally, as well as whether the application is available? If possible, you can manually construct this request and send it to the WAF to observe the status code and response content. Finally, you can try bypassing the WAF and attempt to apply for the certificate directly on the backend application to verify if it works normally.