Certbot NET::ERR_CERT_AUTHORITY_INVALID error

Server
9

Certbot should have take care of everything, but obviously it was not the case. Do you still have the link to the tutorial?

In your apache configuration you should see something like:

SSLCertificateFile      /etc/letsencrypt/live/<domain>/cert.pem
SSLCertificateKeyFile   /etc/letsencrypt/live/<domain>/privkey.pem
SSLCertificateChainFile /etc/letsencrypt/live/<domain>/chain.pem

If the SSLCertificateChainFile directive is missing, you should add it (with the correct file path for chain.pm of course, similar to the other one)

Apparently it's because your apache version is <2.4.8: Recommended Apache config - #4 by _az

If you pass fullchain.pem to SSLCertificateFile in Apache 2.4.8 or newer, it will automatically deal with chaining the intermediate for you.