Getting 'Unknown error' on register

[AntonioCS]

When I click on "Register account" I get:

Unknown error

At the top of the page.
If I go to the letsencrypt/live directory I do see an accounts directory with private and public pem files.

I did a little digging and the only place I can see with the string 'Unknown error' is in file CertificateManager.php line 315.

I did a var_dump of the $response and this is what I see:

array(7) { ["id"]=> int(123) ["key"]=> array(3) { ["kty"]=> string(3) "RSA" ["n"]=> string(683) "o8....." ["e"]=> string(4) "AQAB" } ["contact"]=> array(0) { } ["agreement"]=> string(65) "https://letsencrypt.org/documents/LE-SA-v1.2-November-15-2017.pdf" ["initialIp"]=> string(14) "IP" ["createdAt"]=> string(30) "2018-01-13T19:42:46.779126185Z" ["status"]=> string(5) "valid" }

This has the status as valid so I assume all is good. Why I am I getting the error?
I am using wordpress 4.9.1 (bitnami).