Admins: PLEASE MARK AS PINNED TOPIC FOR COMMUNITY WIKI
(There are too many duplicate postings on this topic)
If you have revd an email with subject line
“Update your client software to continue using Let’s Encrypt”
You probably have a setting in a config file which is pointing to the old renewal server hostname “V01”.
Trying to do an apt-get in hopes of “upgrading” your software will not fix this.
You need to edit the config files for each domain you have.
Try this grep search on your computer/server, from a terminal / command prompt, and you may need to be in superuser mode to search subfolders…
grep -RInwF ‘/etc/’ -e ‘api.letsencrypt’ 2>/dev/null
starting in the folder “/etc” search all subfolders for text string “api.letsencrypt”
send any access denied error messages to trash
results returned should show you .conf files in the subdir / folder named “renewal”
open the .conf file in a text editor
search for the line “server = https://acme-v01.api.letsencrypt.org/directory”
edit it to new value “server = https://acme-v02.api.letsencrypt.org/directory”
repeat for each domain in renewals folder.