If you have a self hosted ERPNext installed using frappe and if you faced the error
Renewal configuration file /etc/letsencrypt/renewal/foobar.spritle.com.conf (cert: foobar.spritle.com) produced an unexpected error: 'Namespace' object has no attribute 'standalone_supported_challenges'. Skipping, then here is the fix for it.
All you got to try is, go to the domain specific config file
then remove or comment the line
standalone_supported_challenges = tls-sni-01,
save the file and
run the command
sudo bench renew-lets-encrypt, you will see the success message
Congratulations, all renewals succeeded
Thanks to kmwenga for the tip.