Error Code: 502 Proxy Error. The request is not supported. (50)

As referenced in my last post, I had a problem with viewing a website. Whenever someone tried to view the site at work they got “Error Code: 502 Proxy Error. The request is not supported. (50)”

The error is coming from Microsoft ISA Sever 2004, to fix this you need to enable the compression filter in ISA Server 2004

Configuration > Add-Ins > tab Web Filters > properties Compression
Filter > select Enable This filer. > Ok > Apply.

This not only fixed the  502 proxy error but also an issue with pages appearing “stripped down” ie only text, no images.