It has long been known that NFS-mounted calendars are not supported. The calendar can be corrupted when more than one person uses the calendar at the same time. If two rpc.cmsd daemons write to the callog file at the same time, the file becomes corrupt. However, two rpc.cmsd daemons could be run simultaneously on the Solaris 2.5.1 release, even though this is not a supported configuration.
With the Solaris 2.6 release, this concurrency is no longer an option. rpc.cmsd does not allow the user to start a calendar that is NFS-mounted and produces the previous error message.