Unable to issue a Let's Encrypt certificate in Domains > example.com > SSL/TLS Certificates > Install > Get it free:
Domain validation failed
Detail: Invalid response from http://example.com/.well-known/acme-challenge/uksG0XWFd8Yd6K51U09HosKjhS7jWF_xEMP5ru_OJ0Y
"<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> n<html xmlns="http"
test.txtfile created in
%plesk_dir%var/acme-challengefolder is accessible via at
http://example.com/.well-known/acme-challenge/test.txtin a web browser.
SSL It! extension is disabled or absent in Extensions > My Extensions.
SSL It! extension was installed and enabled previously.
The common challenge directory is automatically activated when SSL It! extension is installed. After disabling or uninstalling SSL It!, a common challenge directory is still enabled, but Let's Encrypt is unable to use it in standalone mode.
This is SSL It! extension bug with the ID #EXTSSLIT-867, that will be fixed in the next extension updates.
Until the bug will be fixed, apply one of the solutions below: