Read-only, clearErrors and reset

Read-only fields

markReadOnly() freezes the value: setValue becomes a no-op unless you pass force: true, and text typed into a read-only text field is reverted in the same turn. It also aborts a live async round, so a frozen field does not keep transitioning on its own. Everything else still works on a read-only field:

• validate() still validates it, and revalidateSync() still re-runs its rule — freezing a value does not exempt it from the rules.
• reset() still resets it, but keeps readOnly: that is configuration, and configuration changes only through its own API.
• A failedValidation status survives markReadOnly(), so a frozen field that could not be checked still blocks submit; only its lastFailure details are dropped.

AdvancedFormController.markReadOnly() and unmarkReadOnly() reach the whole tree. How a read-only field looks is the widget's business — see Text fields.

setError(null), clearErrors and reset

"Touched" is the flag that lets the validation mode fire: after reset() the field is quiet again until the user edits it or validate() runs. hasFailedValidation on the form clears on any setValue, clearErrors(), reset(), setError(null) or the next validate().

AdvancedFormController has clearErrors() and resetAll() for the whole tree.

Switching validation off instead

To take a section out of the rules while keeping it on screen — invoice details behind an unchecked switch — setValidationEnabled(false) on that subform is better than freezing or detaching it: its errors are cleared, its fields stop counting towards canSubmit and validate(), and everything else — resetAll, markReadOnly, disposal — still reaches it. See Subform patterns.