使用ajax上传文件会返回错误，但使用c＃在asp.net的服务器端正常提交文件

I have a asp.net form that uses ajax for form submit and when I click the button that uploads the files, the alert message in the error in jQuery is being displayed, but when I check the files on the server, the files are being uploaded with no problem.I have a asp.net form that uses ajax for form s