Please post your issue in a new forum post rather than bumping up an old thread from 2018.
https://www.wix.com/corvid/reference/$w.UploadButton.html
https://support.wix.com/en/article/adding-and-setting-up-an-upload-button
https://support.wix.com/en/article/corvid-tutorial-using-the-upload-button-with-code
Old post being closed.