Restriction of cancelled project

Frappe Cloud
1

Want to restrict cancelled project while new entries to avoid wrong posting of entries

2

Welcome @Rachana_Dange:

Use client script to override link queries … something like this in, i.e, Purchase Order.
Here trigger set_query on “company” field change, because core code consider other filters too (related to cost center, etc …)

frappe.ui.form.on("Purchase Order", "company", function(frm) {
    
    frm.set_query("project", function() {
        return {
            "filters": [
                ["Project", "status", "!=", "Cancelled"]
            ]
        };
    });
});

See this:

https://frappeframework.com/docs/user/en/guides/app-development/overriding-link-query-by-custom-script

Anyway, each case (doctype) would be different.
Hope this helps.