How do I resolve the following error message: The referenced model containing messages crossing model boundaries must be at root-level.

I receive an obscure error message when updating my test harness in R2017b:

Invalid use of referenced model <model_name>.  The referenced model containing messages crossing model boundaries must be at root-level.

What is the reason for this error message?

Answer 1

[MathWorks Support Team]

This error message is likely the result of messages being used as inputs and/or outputs to model references.  There are certain limitations for using Messages in Simulink R2017b:

• Moore charts
• Atomic subcharts
• Breakpoint condition expressions
• Model reference inputs and outputs

However, using model reference inputs and outputs is possible in R2019b release.