Can't access workflow properties

[Sangram]

you can find next_workflow_state on validate event. on every workflow action, the document gets Saved.
So, you can capture Next State on validate.

Check this thread

HOW TO: Validation for Custom Workflow

The following code will only allow a user with the authorized user role to modify the document. frappe.ui.form.on("Doctype", "Trigger", function (frm) { if (user_roles.indexOf("Authorized User Role") !== 0 && frm.doc.workflow_state == "Enter desired workflow state") { msgprint("Message to be printed"); frm.disable_save(); } });