The complete form structure. #process, #after_build, #element_validate, and other handlers being invoked on a form element may use this reference

Stores the gathered validation handlers. This property is uncacheable. Type:

public FormStateInterface::setLimitValidationErrors($limit_va

public FormStateInterface::unsetValue($key)

public FormStateInterface::setError(array &$element, $message

public FormStateDecoratorBase::setSubmitted()

public FormStateInterface::setTemporaryValue($key, $value)

public FormBuilderInterface::submitForm($form_arg, FormStateInterface

The form element that triggered submission, which may or may not be a button (in the case of Ajax forms). This key is often used to distinguish between various buttons in a

public static EnforcedResponse::createFromException(\Exception $e)