Solution for “Request Entity Too Large” error

IIS has a limit for the size of the files users can upload to an application. If the file size exceeds the limit, the application will throw “Error in HTTP request, received HTTP status 413 (Request Entity Too Large)” error.

The default file upload size is 49 KB (49152 bytes). The application records the log below if user tries to upload a file that is bigger than this size.

Why this issue occurs for SSL sites? The reason is that the request body must be preloaded during the SSL handshake process.

Solution

The quickest solution is to increase the upload size limit. IIS uses uploadReadAheadSize parameter in applicationHost.config and web.config files to control this limit.

uploadReadAheadSize
Optional uint attribute.
Specifies the number of bytes that a Web server will read into a buffer and pass to an ISAPI extension or module. This occurs once per client request. The ISAPI extension or module receives any additional data directly from the client. The value must be between 0 and 2147483647.
The default value is 49152.

Server Runtime

Steps to change the value of this parameter:

1. Open IIS Manager
2. Select the site
3. Double click “Configuration Editor”
4. Select system.webServer and then serverRuntime
5. Modify the uploadReadAheadSize value
6. Click “Apply”

You may also want to change maxRequestEntityAllowed parameter. It specifies the maximum number of bytes allowed in the request body.

Note: In another case, the recommendations above didn't work to solve 413 error. Please check this post for more information