搞定了。在backend/config/bootstrap.php配置文件中增加图片存放路径`
Yii::setAlias('@basePath', dirname(DIR).'/web/uploads/img/');
Yii::setAlias('@baseUrl', $_SERVER['REQUEST_SCHEME']."://".$_SERVER['HTTP_HOST'].'/uploads/img/');

在yidashi/yii2-uploader/src/actions/UploadAction.php类中修改```
public function init()
    {
        if (Yii::$app->request->get($this->uploadQueryParam)) {
            $this->uploadParam = Yii::$app->request->get($this->uploadQueryParam);
        }
        if ($this->uploadOnlyImage !== true) {
            $this->_validator = 'file';
        }
        $this->basePath = Yii::getAlias('@basePath');//Yii::getAlias($this->basePath);源码使用
        $this->baseUrl = Yii::getAlias('@baseUrl');//Yii::getAlias($this->baseUrl);
    }

"name": "PHP Warning",

"message": "move_uploaded_file(//123.png): failed to open stream: No such file or directory",
"code": 2,
"type": "yii\\base\\ErrorException",
"file": "D:\\www\\yii2-test\\vendor\\yiisoft\\yii2\\web\\UploadedFile.php",
"line": 163,

请问还要配置其他地方吗，上传报"name":"PHP Warning","message":"move_uploaded_file(//123.png): failed to open stream: No such file or directory","code":2

使用yii2-uploader报500 Internal Server Error错误

使用yidashi/yii2-uploader上传图片报