Failed to renew Lets' encrypt certificate

I manually installed the certificate. Maybe the problem is Virtualmin not having updated features yet.

But I can’t import the certificate in Virtualmmin in the tab:

Server Configuration> SSL Certificate> Update Certificate

I select the two files fullchain.perm, privkey.perrm and if I press “Update” the following error appears:

Certificate installation failed: Missing or invalid signed SSL certificate: Line 30 does not look like PEM format.

Do you have any idea what the problem is?
Thank you