I just upgraded to Symfony 3.0.4 and I can't set integers as choice values in ChoiceType field. Validation gives me "This value is not valid." message for an integer value. In my case it was default value passed through "empty_data" option.

Here is example field I use to reproduce this:

$builder->add('emailNotificationsEnabled', ChoiceType::class, [
    'required' => false,
    'multiple' => false,
    'choices'  => [0, 1],
    'empty_data' => 1,
]);

I found out that this is caused by this change: 3eac469#diff-81585954baecb0c458557b7969974093L42