Symfony 4：FMElfinderBundle上传图片空白页

Question

我使用FMElfinderBundle在我的博客中上传图片。 但是，当我想“浏览服务器”以上传图像时，出现以下错误的空白页：

enter image description here

#config/packages/fm_elfinder.yaml

fm_elfinder:
assets_path: "/public/uploads/images/post_img" # Le dossier configuré dans composer.json
instances:
    ckeditor:
        locale:           "%locale%"
        editor:           "ckeditor"
        fullscreen:       false
        include_assets:   true
        connector:
            debug:        false
            roots:
                uploads:
                    driver:           "LocalFileSystem"
                    path:             "/public/uploads/images/post_img"
                    upload_allow:     ['image/png', 'image/jpg', 'image/jpeg', 'image/gif', 'application/zip', 'audio/mpeg', 'text/csv', 'video/mp4', 'video/webm', 'application/pdf']
                    upload_deny:      ['all']
                    upload_max_size:  "8M"

谢谢您的帮助！