In ASP.Net, while uploading large files using FileUpload control, you may have experienced an error saying that "Maximum request length exceeded". The default value of Maximum upload file size is set to 4 MB. In most cases, this limit is set to avoid DDoS attacks, large file uploads and few other reasons. So, when you try to upload a file with a size larger than 4 MB, you will start seeing this error.

Server Error in '/' Application.
------------------------------
Maximum request length exceeded.

 

Solution :

The default maximum file upload size for IIS is 4MB. Uploading more than 4MB file will give an error "Maximum request length exceeded"
 
machine.config file is set to a 4 MB default limit. We can change it to 20MB using the following code in the web.config.
 
< system.web >
     < httpRuntime executionTimeout="240" maxRequestLength="20480" / >
< /system.web >

 

For IIS 7 and later versions, we can modify the default upload limit to 30 MB. You will need to add the following code to the web.config.

< system.webServer >
     < security >
         < requestFiltering >
              < requestLimits maxAllowedContentLength="3000000000" / >
         < /requestFiltering >
     < /security >
< /system.webServer >


Note:

maxAllowedContentLength is estimated in bytes
maxRequestLength is estimated in kilobytes.

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