This message is generated when operations that require a notebook front end are evaluated in a Wolfram Language kernel that is not connected to a notebook front end.
This message can be generated by functions that manipulate notebooks, such as NotebookPut and SelectionEvaluate, and functions that use the notebook front end, such as ConvertToPostScript.
This message is normally seen only when using the Wolfram Language kernel without a notebook front end. If you see this message in a situation where it is not expected, please contact Technical Support.
Off[message] switches off the message; On[message] switches it on. For example: Off[FrontEndObject::notavail].