http://ayende.comAyende @ RahienCopyright (C) Ayende Rahien 2004 - 2021 (c) 202660There has been some changes in .NET 4 which introduced this bug. I hit it when we switched our solution to VS2010. So as it's actually forgetting to check HttpContext.Current null values before using it, we hacked this by assigning a mock HttpContext around it. Sebastien http://ayende.com/4599/hunt-the-bug#comment5http://ayende.com/4599/hunt-the-bug#comment5Sat, 21 Aug 2010 14:14:33 GMTThis means that the context _is_ available but it is a fake one - getting the response throws. My workaround that I posted is still valid ;-) http://ayende.com/4599/hunt-the-bug#comment4http://ayende.com/4599/hunt-the-bug#comment4Sat, 21 Aug 2010 14:10:28 GMTYep, starting .NET 4 HttpUtility requires a HttpContext /HttpResponse wich is not yet available at the time of Application_Start with IIS7 in integrated mode. I guess the stack trace looks like: [HttpException (0x80004005): Response is not available in this context.] System.Web.HttpContext.get_Response() +8753496 System.Web.Util.HttpEncoder.get_Current() +39 System.Web.HttpUtility.UrlEncodeToBytes(String str, Encoding e) +31 System.Web.HttpUtility.UrlEncode(String str) +41 Global.Application_Start(Object sender, EventArgs e) http://ayende.com/4599/hunt-the-bug#comment3http://ayende.com/4599/hunt-the-bug#comment3Sat, 21 Aug 2010 11:40:03 GMTI'm guessing that HttpUtility underneath requires an HttpContext and that might not be present at Application_Start. http://ayende.com/4599/hunt-the-bug#comment2http://ayende.com/4599/hunt-the-bug#comment2Sat, 21 Aug 2010 11:16:49 GMTI guess it has to do with the new HttpEncoder support. I can be disabled by setting Response.DisableCustomHttpEncoder but that is not available in application start. You could have used HttpEncoder.Default however. http://ayende.com/4599/hunt-the-bug#comment1http://ayende.com/4599/hunt-the-bug#comment1Sat, 21 Aug 2010 09:31:36 GMT