File Upload Limit Issue in asp.net mvc

I have fixed my file upload file size as 50MB using the following code

< httpRuntime executionTimeout="60" maxRequestLength="51200"/> in Web.cofig file.

When i am uploading more than 25MB file it displays error message as "file or directory not found". How to fix thi开发者_高级运维s issue?

This issue will occur because of timeout reached or IIS upload limit reached.