This error is happening when Unity is trying to create a Identified Subscriber Message(ISM). These are messages from identified extensions that have not logged into their mailboxes.
For some reason the creation of the message is failing. Are there any other errors around it? If not, we might need to setup some diags and watch for them to see what is going on.
If the subscriber message create fails, the message is not lost, it gets sent out as a regular outside caller message, i.e. the recipient will see the message as one coming from the Unity Mailbox rather than a Unity subscriber.
Are you getting this error “Installer User Interface Mode Not Supported. The installer cannot run in this UI mode. To specify the interface mode, use the -i command-line option, followed by the UI mode identifier. The value UI mode identifiers...
The below trick might come handy when you have to add a new node to a cluster but you don't have or is unsure of the security password for the publisher. This procedure has been around for ages.
1) Login into the CLI of the Publisher.