Assuming either #21656, #21267 or #21880 broke the expected behaviour of Doctrine Bridge's EntityType.

Assumptions:

• You have an entity called AppBundle\Entity\Foo with correct annotations - fields: id, name
• The database schema has been updated to reflect the entity
• There is one row in the database table with ID 1
• CSRF disabled for brevity

Use case:

• Create a form called "bar", add an EntityType widget with the name "foo"; set "class" to "AppBundle:Foo"; set "choice_label" to "name"; set "multiple" to "true", set "invalid_message" to "Invalid value: {{ value }}".
• Post the following data to the form: bar[foo][]=1
• Evalulate $form->isValid()

Expected:

• Evaluates to boolean true.

Actual:

• Evalulates to boolean false - form errors state that for field "foo", the error is "Invalid value: array".

I rolled back to Symfony 3.2.4 and received the expected outcome of $form->isValid() evaluating to boolean true.