We have recently been experiencing an issue with IE9 in our environment. When a user tries to access a web page which is blocked by the proxy server they are redirected via a 302 to a block page on a specific port. This block page should itself be proxied as it has a specific section within the PAC file that instructs the browser to access this URL via the proxy.
When using Chrome, Firefox, IE8, IE10 or IE11 this works perfectly. When using IE9 the browser tries to go directly to the block page URL, rather than parsing the PAC file and sending the request to the proxy.
After extensive searching I have been unable to find this documented anywhere. Any help would be appreciated.
Regards,
Jeremy.