In this article I will explain and provide solution about why AJAX File Upload does not work with Web Methods (Page Methods) in ASP.Net using C# and VB.Net.
When we try to upload a File using Form Data and jQuery AJAX using a Web Method (Page Method), it does not work.
By default, ASP.Net Web Methods (Page Methods) are only allowed to handle calls for Content Type application/json.
In contrast, File upload process requires the Content Type to be set as multipart/form-data.
Thus, it is not possible to upload a File using a Web Method (Page Method) in ASP.Net.
There are two alternative solutions which will surely solve the above problem.
1. Web Service
You can create a Web Service and then use its Web Method for uploading Files using Form Data and AJAX. The following article provides detailed information on uploading Files using a Web Service in ASP.Net.
2. Generic Handler
Another solution is to use a Generic Handler for uploading Files using Form Data and AJAX. The following article provides detailed information on uploading Files using a Generic Handler in ASP.Net.