File Upload Dropzone

Accessibility

The drop zone component builds on the native HTML <input type="upload"> element. It includes a visual <button> and/or a drag-and-drop area that can receive keyboard focus.
Make sure the user can interact with the file uploader and the drag-and-drop region. To give the input keyboard focus, use the tab key (or shift + tab when tabbing backwards) To activate the input, use the enter/return or space keys.
Provide clear and informative error messaging to allow user to understand what he needs to do to rectify the problem.