form group: a rule pins the member "{id}", b...

Warnings reference › form.group.unknown-member:*

Identifier

form.group.unknown-member:*

Raised by

form

Since

1.100.0

What happened

A visibleWhen/readOnlyWhen/requiredWhen condition names a member with { form: id, name }, but no member was added with that id (or the member left the group). The rule evaluates against an empty value, exactly as an unknown field name does.

The fix

Add the member with the id the rule pins, or correct the id in the rule.

The smallest fix

const group = createFormGroup();
group.add(header, { id: 'header' }); // a rule with { form: 'header' } now resolves

Reference

Covered in full at the API reference.