'Name contains invalid characters' error when adding A record for Let's Encrypt wildcard SSL cert

The challenge you're referencing is a way for Let's Encrypt to validate you own the domain.

https://letsencrypt.org/docs/challenge-types/

To confirm, are you adding the below as the TXT record, with no (*) in the front?

_acme-challenge.example.website

The reason I ask is because I was only able to replicate the "name contains invalid characters" error by adding the wildcard * in front while adding the TXT record:

*_acme-challenge.example.website

In other words, it's not meant to be the wildcard records itself. You would just need to add the above as the TXT record, with no * at all.

Thank you.

Just to be clear, when adding the TXT record in the Domains manager, is _acme-challenge.example.website the value?

In that case what is the host?

@jimlongo when creating a new TXT record using DNS Manager, the Hostname field corresponds to the subdomain you want to have returning an entry to the the Value field.

So, in your case, using DNS Manager for the zone example.website, you'd create a new TXT Record with the following entries:

Hostname: _acme-challenge
Value: TheValueRequiredByLetsEncrypt

After your settings have propagated, you can check that your TXT record is correctly configured using dig:

$ dig _acme-challenge.example.website TXT +short
"TheValueRequiredByLetsEncrypt"