The RSL SSL-certificate is no more verified at the authorization centre, for the centre has stopped providing its services for Russian organizations. So viewing dissertations to which the access is restricted has become unavailable at VRRs.
We did modify the software for VRR activation, thus the problem is solved. To restore the system operation, VRR administrators are to remove the previous activation service and to install the new version (which is now available on the link of the guide).