Error when Uploading files

Hi, the page admin-ajax.php is loaded with the following error displayed in it when I click the ‘Start Upload’. Do you have an idea how I could fix this?

{“files”:[{“name”:”1429812573-0241″,”size”:0,”type”:””,”error”:”No file was uploaded”}]}

https://ww.wp.xz.cn/plugins/work-the-flow-file-upload/