Erro ao usar chave estrangeira para referenciar id

Estou com erros ao tentar referenciar uma chave estrangeira. Tenho Autor e Livro, e não estou conseguindo colocar autor_id como chave estrangeira referenciando o id de Autor na migration do Livro

Meu código:

Migrations do Livro

public function up()
    {
        Schema::create('livros', function(Blueprint $table) {
            $table->bigIncrements('id');
            $table->string('title', 30);
            $table->string('about', 30);
            $table->string('company', 30);
            $table->string('edition', 4);
            #$table->bigInteger('autor_id');

            $table->timestamps();

        });
    }

public function up()
    {
        Schema::table('livros', function(Blueprint $table) {
            $table->bigInteger('autor_id');
            $table->foreign('autor_id')->references('id')->on('autores');

        });
    }

Migration do Autor:

public function up()
    {
        Schema::create('autores', function(Blueprint $table) {
            $table->bigIncrements('id');
            $table->string('name');
            $table->string('surname');
            $table->string('genre');
            $table->integer('books_number');
            $table->timestamps();
        });

    }

O erro:

 Illuminate\Database\QueryException  : SQLSTATE[HY000]: General error: 1215 Cannot add foreign key constraint (SQL: alter table `livros` add constraint `livros_autor_id_foreign` foreign key (`autor_id`) references `autores` (`id`))

  at /home/raiany/Documentos/Programming/Php/CRUD-books/vendor/laravel/framework/src/Illuminate/Database/Connection.php:669
    665|         // If an exception occurs when attempting to run a query, we'll format the error
    666|         // message to include the bindings with SQL, which will make this exception a
    667|         // lot more helpful to the developer instead of just the database's errors.
    668|         catch (Exception $e) {
  > 669|             throw new QueryException(
    670|                 $query, $this->prepareBindings($bindings), $e
    671|             );
    672|         }
    673| 

  Exception trace:

  1   Doctrine\DBAL\Driver\PDOException::("SQLSTATE[HY000]: General error: 1215 Cannot add foreign key constraint")
      /home/raiany/Documentos/Programming/Php/CRUD-books/vendor/doctrine/dbal/lib/Doctrine/DBAL/Driver/PDOStatement.php:123

  2   PDOException::("SQLSTATE[HY000]: General error: 1215 Cannot add foreign key constraint")
      /home/raiany/Documentos/Programming/Php/CRUD-books/vendor/doctrine/dbal/lib/Doctrine/DBAL/Driver/PDOStatement.php:121