Problem sharing calendar

Hi, I have been running my NC instance for a couple of months. At first, I could share my calendar, and sync it with Thunderbird.

But now, after the update to NC 25, when I try to share the same calendar (using the share button inside the “Edit calendar”, or through the CalDAV option) it shows me a pop up saying the link couldn’t be copied to my clipboard.

Is there a problem in the sharing configuration (though i haven’t changed the settings after the initial setup)? Or, what can be the problem?

Thanks in advance.