dokku-letsencrypt: Wrong directory fields

I’m getting a weird error on one of the domains: DeserializationError: Deserialization error: Wrong directory fields. Googling produces nothing.

I have other domains with letsencrypt on this server and they work fine.

Any ideas?

root@dokku ~ # dokku config:set --no-restart exampleapp.com DOKKU_LETSENCRYPT_EMAIL=myemail@provider.com
-----> Setting config vars
       DOKKU_LETSENCRYPT_EMAIL: myemail@provider.com

root@dokku ~ # dokku letsencrypt exampleapp.com
=====> Let's Encrypt exampleapp.com
-----> Updating letsencrypt docker image...
latest: Pulling from dokkupaas/letsencrypt-simp_le
420890c9e918: Already exists
e4a2ae244258: Already exists
5c6ac6d1c950: Already exists
Digest: sha256:18a19b34beceba79dd5be458abe7e132fc7486da1da19cc4d0395ad4578031ef
Status: Image is up to date for dokkupaas/letsencrypt-simp_le:latest
       done updating
-----> Enabling ACME proxy for exampleapp.com...
-----> Getting letsencrypt certificate for exampleapp.com...
        - Domain 'exampleapp.com'
darkhttpd/1.11, copyright (c) 2003-2015 Emil Mikulic.
listening on: http://0.0.0.0:80/
2016-12-09 08:06:47,751:INFO:__main__:1211: Generating new account key
2016-12-09 08:06:48,554:INFO:requests.packages.urllib3.connectionpool:758: Starting new HTTPS connection (1): acme-v01.api.letsencrypt.org
Traceback (most recent call last):
  File "/simp_le-master/simp_le.py", line 1401, in main
    return main_with_exceptions(cli_args)
  File "/simp_le-master/simp_le.py", line 1386, in main_with_exceptions
    persist_new_data(args, existing_data)
  File "/simp_le-master/simp_le.py", line 1282, in persist_new_data
    client = registered_client(args, existing_data.account_key)
  File "/simp_le-master/simp_le.py", line 1224, in registered_client
    client = acme_client.Client(directory=args.server, key=key, net=net)
  File "/usr/lib/python2.7/site-packages/acme/client.py", line 63, in __init__
    self.net.get(directory).json())
  File "/usr/lib/python2.7/site-packages/acme/messages.py", line 169, in from_json
    raise jose.DeserializationError(str(error))
DeserializationError: Deserialization error: Wrong directory fields

Unhandled error has happened, traceback is above

Debugging tips: -v improves output verbosity. Help is available under --help.
-----> Certificate retrieval failed!
-----> Disabling ACME proxy for exampleapp.com...
       done