Node Validation Show Error Message for Invalid Connection

Hello!

I have been trying different things following https://gojs.net/latest/intro/validation.html to get an error message to show up when a node is attempting to connect to a port that is invalid. Is it possible?

Thank you,

I assume you mean when a user is trying to draw a new link and link validation causes a failure to connect.

See https://gojs.net/extras/linkValidationToolTip.html