This week's book giveaway is in the Mac OS forum. We're giving away four copies of a choice of "Take Control of Upgrading to Yosemite" or "Take Control of Automating Your Mac" and have Joe Kissell on-line! See this thread for details.
U said that there are lot of html statements before redirect. This means that you are writting to the response. There may be a situation in your case that the response is alredy committed ( output is written to the response and it is flushed). Therfore it is throwing an Exception.