Admin filepicker - Network error

Support
1

Hi,

The filepicker does not work in the admin.

On pageload and when clicking it, the following error message appears:

Fetch Failed:
NetworkError when attempting to fetch resource.

And the browser console logs this error:

NetworkError when attempting to fetch resource. at admin.min.js:4:5928
    s http://localhost:8000/user/plugins/admin/themes/grav/js/admin.min.js?9f48728897:4

Here is my .yaml:

form:

  fields:

    tabs:
      type: tabs
      active: 1

      fields:
        content:
          type: tab
          title: PLUGIN_ADMIN.CONTENT

          fields:
            xss_check:
              type: xss

            details:
              type: section
              title: Details

            header.selected:
              type: filepicker
              label: Image
              folder: '@self'
              preview_images: true
              accept:
                - .png
                - .jpg

            header.media_order:
              type: pagemedia
              label: PLUGIN_ADMIN.PAGE_MEDIA

Version: Grav v1.6.9 - Admin v1.9.4