your properties in your entities are protected but you have not created getters/setters for them. ( or you have not pasted your full code )
Therefore the form-builder is not able to access your user's properties.
At least the public function setId($id)
in User.php is definitely missing!
That's why the exception is thrown saying:
Maybe you should create the method "setId()"?
Create getters and settes for every property using ...
app/console doctrine:generate:entities
or create them by hand...
User.php
public function getId()
{
return $this->id;
}
public function setId($id)
{
$this->id = $id;
return $this;
}
// ...