Traefik: Unable to obtain ACME certificate for domains

Traefik: Unable to obtain ACME certificate for domains

I'm using traefik for providing some services on my NAS with https using lets encrypt. Now I noticed that the tls certs of my nextcloud installation expired yesterday evening. Traefik had logs like this: 
time="2018-08-31T22:43:08Z" level=error msg="Error getting ACME client: ACME client still not built, retrying in 6.83135832s"
time="2018-08-31T22:43:15Z" level=error msg="Error getting ACME client: ACME client still not built, retrying in 12.680203952s"
time="2018-08-31T22:43:28Z" level=error msg="Error getting ACME client: ACME client still not built"

I updated to v1.7 but now the error is different: 
time="2018-09-01T07:42:44Z" level=error msg="Unable to obtain ACME certificate for domains \"my.domain\" detected thanks to rule \"Host:cloud.dnas.one\" : cannot get ACME client ACME challenge not specified, please select TLS or HTTP or DNS Challenge"

This message is posted for every domain, internal as well as externals. Couldn't find much information about this issue. 
Traefik configuration:
defaultEntryPoints = ["http", "https"]
idleTimeout = 0
dialTimeout = 0
logLevel = "WARN"

[entryPoints]

[entryPoints.http]
address = ":80"

#entryPoint = "https"

[entryPoints.https]
address = ":443"
[entryPoints.https.tls]

# Lets Encrypt via ACME
[acme]
email = "my@email.de"
storage = "acme.json"
entryPoint = "https"
onDemand = false
OnHostRule = true
caServer = "https://acme-v02.api.letsencrypt.org/directory"

[docker]
endpoint = "unix:///var/run/docker.sock"
domain = "nas.one"
watch = true

Solutions/Answers:

Solution 1:

Your traefik.toml file hasn’t specified the challenge method with which it is supposed to get the certificates from Let’s Encrypt. The 1.7 error message is more clear about that.

If you want to use the HTTP challenge, add the following lines:

[acme.httpChallenge]
  entryPoint = "http"

If you want to use the DNS challenge (Required if you want to use wildcard certificates), add the following lines:

[acme.dnsChallenge]
  provider = "YOURPROVIDER"
  delayBeforeCheck = 0

Check the documentation for the rest of the configuraiton.

References

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