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Uploading Large Files

RadUpload has been replaced by RadAsyncUpload, Telerik’s next-generation ASP.NET upload component. If you are considering Telerik’s Upload control for new development, check out the documentation of RadAsyncUpload or the control’s product page. If you are already using RadUpload in your projects, you may be interested in reading how easy the transition to RadAsyncUpload is and how you can benefit from it in this blog post. The official support for RadUpload has been discontinued in June 2013 (Q2’13), although it is still be available in the suite. We deeply believe that RadAsyncUpload can better serve your upload needs and we kindly ask you to transition to it to make sure you take advantage of its support and the new features we constantly add to it.

You can upload files with a combined size of up to 2GB, but it requires some modifications in your application configuration files.

The configuration file sections and attributes are case sensitive . This means that the sections and attributes below will be incorrect if written using a case other than shown.

Web.config settings

The following attributes can be assigned to the <httpRuntime> tag in the <system.web> section of the Web.config file.


Specifies the limit for the input stream buffering threshold, in KB. This limit can be used to prevent denial of service attacks that are caused, for example, by users posting large files to the server. The default value is 4096 (4 MB).

To enable large file uploads you need to change the value of this attribute to the largest allowed combined file size for your application. If someone selects and uploads files with total size larger than maxRequestLength, this will result in a "Page not found" error (which is the default error of the Framework). RadUpload does not provide a way for handling this error.

The MaxFileSize property of the RadUpload control specifies the maximum size for each of the uploaded files in bytes .


Specifies the maximum number of seconds that a request is allowed to execute before being automatically shut down by ASP.NET. The value of this setting is ignored in debug mode. The default in .NET Framework 2.0 is 110 seconds. In the .NET Framework 1.0 and 1.1, the default is 90 seconds.

To enable large file uploads, which can take large periods of time, increase the value of this property.

You can find more information about the httpRuntime configuration in the following MSDN article:

How to modify web.config

To make the above modifications to your application for large file uploads you need to:

  1. Open the Solution Explorer, navigate to the application web.config file and open it.

  2. Under the <configuration> element locate the <system.web> element. Add it if it does not exist.

  3. Under the <system.web> element locate the <httpRuntime> element. Add it if it does not exist.

  4. In the <httpRuntime> element locate the maxRequestLength and executionTimeout attributes. If they do not exist, add them and set their values:

<httpRuntime maxRequestLength="102400" executionTimeout="3600" />

The configuration, allowing uploads of files up to 100MB and upload periods up to 1 hour, should look like the following:


      <httpRuntime maxRequestLength="102400" executionTimeout= "3600" />

Settings for IIS7

  • Add these lines in the web.config file:
<security >
        <requestLimits maxAllowedContentLength="1024000000" />
  • Open the file C:\Windows\System32\inetsrv\config\applicationHost.config and find the line: <section name="requestFiltering" overrideModeDefault="Deny" />

  • Set the overrideModeDefault property to Allow. So now the line should look like: <section name="requestFiltering" overrideModeDefault="Allow" />

Machine.config settings

The following attributes can be assigned in the <processModel> element of the machine.config file. They must be set at the machine level, not the application level in web.config.

These properties affect any response deadlock in ASP.NET, not just the application that uploads large files, and should be used with caution.


Specifies the time interval, in the format HH:MM:SS, after which the process is restarted if the following conditions are met:

  • There are queued requests.

  • There has not been a response during this interval. The default is 3 minutes. To allow very large uploads, you may have to increase this value.


Specifies the time, in the format HH:MM:SS, that must elapse after the last restart to cure a deadlock before the process is restarted to cure a deadlock again. This prevents thrashing on processes that require a relatively long startup time. The default is 9 minutes. To allow very large uploads, you may have to increase this value.

Other settings


Sometimes when the application is hosted on Windows Server 2003, the above settings do not seem to have effect. In this case you must modify the IIS metadata file, particularly the AspMaxRequestEntityAllowed property. You can find more information about that in the following KB article:

Microsoft URLScan

If you are using Microsoft URLScan you will need to modify its urlscan.ini and set MaxAllowedContentLength to an appropriate value.

Third party network monitoring software

If you are using any third party network monitoring software you should ensure that it is properly configured to allow file uploads with the needed length and content. For more information please, contact your network administrator.

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