Note: This article has the reference to the issue with the fix available:
"The extension was not able to renew certificates,
issued before updating the extension to version 2.0 for domain names with uppercase letters."
- Let’s Encrypt 2.2.0 11 July 2017
On domains with capital letter(s) Let's Encrypt certificate renew fails with error:
PLESK_ERROR: Cannot renew certificate on domain Example.com with error: Install certificate failure: Unable to set certificate name:
It is not possible to renew certificates that were generated by Let's Encrypt 1.9 or below. Certificates that were generated by Let's Encrypt 2.0 and above can be renewed.
Extension bug EXTLETSENC-211. Fixed in 2.2.0 version.
Update Let's Encrypt extension to the latest one.