how to troubleshoot post error 400 "challenge or authorization must be in pending state"

Hi,

We use dehydrated with EAB and dns validation and it used to work like a charm.
After switching to a new acme endpoint we get :
```
+ Responding to challenge for hostname.com authorization...
+ ERROR: An error occurred while sending post-request to https://acme-v02.harica.gr/acme/ (Status 400)

Details:
HTTP/1.1 100 Continue

HTTP/1.1 400 Bad Request
Date: Wed, 08 Apr 2026 06:58:31 GMT
Server: Apache
Strict-Transport-Security: max-age=63072000; includeSubDomains; preload
Content-Type: application/problem+json
Content-Length: 119
X-Frame-Options: sameorigin
X-XSS-Protection: 1; mode=block
Connection: close

{
"type": "urn:ietf:params:acme:error:malformed",
"detail": "challenge or authorization must be in pending state"
}

EXPECTED value GOT EOF
```

this happens after the txt records are checked. (if I use the EAB in certbot I get a certificate)
I checked with API=1 and API=2

Is there a way to see what is malformed?

OS/RPM: RHEL8, openssl-1.1.1k, dehydrated.noarch 0.7.1-6.el8

Start by reproducing the failure with dehydrated 0.7.1, the HARICA ACME endpoint, EAB, DNS validation, and API=1 and API=2 after the TXT records are checked. Compare the failing dehydrated request with the successful certbot flow; done means identifying a specific malformed request or endpoint-compatibility issue and documenting the evidence.

Written by the indexing model from the issue text.