Symfony 4 Unable to transform value for property path "furnace": Expected a Boolean. what is this error how to fix?

Question

symfony

Good afternoon, forum, the
torment with Symfony continues :-( Created CRUD, all boolean fields (except for the index), in the mysql database
(Data_Type: tinyint [0|1]).
, even before the opening of the form does not reach
how to fix please tell me?

Answer 1

Found an error!
strange, did everything through the entity console too.
but for some reason this is generated:

public function getFurnace(): ?string
    {
        return $this->furnace;

    }

changed to:

public function getFurnace(): ?bool
    {
        return $this->furnace;

    }

and everything went!!