This message is generated when a value of the indicated symbol includes a reference to an InputStream or OutputStream expression or to a WSTP connection.
Expressions that refer to files or links outside of the Wolfram System cannot in general be saved in an output file, since those files or links may be different in a new Wolfram System session.
Off[message] switches off the message; On[message] switches it on. For example: Off[DumpSave::outref].
Examples
Basic Examples(1)
The stream information in the value of the indicated symbol is not saved: