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Unfortunately, that is not the problem. The problem was the failure to expand the coverage of the certificate to include the new domains musingsofamaverick.blog and www.musingsofamaverick.blog. Following the instructions in using the command certbot --expand, I received the error message above and my certificate does not cover the new domain names.
The subdomains www were actually included for both domains in the the original instruction so that there should now be four domain names covered by the certificate.
--expand tells Certbot to update an existing certificate with a new certificate that contains all of the old domains and one or more additional new domains. With the --expand option, use the -d option to specify all existing domains and one or more new domains.
All 4 domain names are for the same website. Essentially they are aliases that should point to the same content. They are: musingsofamaverick.org, www.musingsofamaverick.org, musingsofamaverick.blog, www.musingsofamaverick.blog
To the best of my knowledge, I do not have a virtual host.
The instructions you cite are the instructions I followed. I am not sure what you mean by the last sentence as I only entered -d once at the beginning of the domain name list. I did not enter -d before each domain name.
Looking at my installed certbot packages with Synaptic I find that only certbot and python3-certbot are installed. Python-cerbot-nginx does not appear to be installed.
To solve the problem on my LEMP server all I had to do was to install the nginx plugin and re-run the --expand command. Since certbot was already installed all I had to do was run
and my certificate was expanded to include the new domain. (It was not necessary to put the -d in front of every domain name. I just separated each domain name with a comma and no space.)