SSL certificate problem

Hello everyone,
I can't activate the SSL certificate on a domain (Shared CDN ), the system gives me the following message: "An error occurred while changing the domain associated with your shared hosting."
With the www subdomain I have not encountered any problems and the certificate has been activated correctly and without any problems.
No problem with all other domains and subdomains.
Some idea?

Hello @MarinkoB,

what is the domain name concerned please?

^FabL