Knowledge Base

Unable to download ISO images using Microsoft Download Manager


When trying todownload ISO images from Microsoft Licensing portal, it fails with an error message “server error”. 

While downloading large files, the file is downloaded in multiple sections. To support this kind of download, HTTP 1.1 Content-Range header is used. If the server is behind a proxy server or a firewall that removes this header, the download will be unsuccessful.


SonicWall uses the feature “Enable HTTP Byte-Range requests with Gateway AV” to suppress the use of HTTP Byte-Range requests to prevent the sectional retrieval and reassembly of the potentially malicious content. This is done by terminating the connection and thus preventing the user from receiving the malicious payload. If this feature is disabled on  Sonicwall downloading ISO images using Microsoft download manager can fail.

In order to Enable HTTP Byte-Range requests with Gateway AV, follow these steps:

1.Login to SonicWall management interface.
2. Go to Security services | Gateway Anti-Virus , Click on the Configure Gateway AV settings button.
3. Click to select the Enable HTTP Byte-Range request with Gateway AV check box.


  4.Click Ok.

More information:

For more information refer Microsoft article http://support.microsoft.com/kb/922330