我试图将外键添加到laravel中的一个表中，我遇到了这个错误

In Connection.php line 664:

  SQLSTATE[HY000]: General error: 1215 Cannot add foreign key constraint (SQL
  : alter table `bugFix` add constraint `bugfix_project_id_foreign` foreign k
  ey (`project_id`) references `Project` (`id`))

In Connection.php line 458:

  SQLSTATE[HY000]: General error: 1215 Cannot add foreign key constraint

我搜索了与ine类似的问题，每个人都要求将数据库引擎设置为innodb，我也这样做了，但错误仍然存在。这是我创建错误修复表的迁移脚本

public function up()
{
    Schema::create('bugFix', function (Blueprint $table) {
        $table->engine = 'InnoDB';
        ...
        $table->unsignedInteger('project_id');
        ...
        $table->foreign('project_id')
          ->references('id')->on('Project');
        ...
    });
}

这是创建项目表的脚本

public function up()
{
    Schema::create('project', function (Blueprint $table) {
        $table->engine = 'InnoDB';
        // Project document information
        $table->increments('id');
        ...
    });
}