Today the error we have resolved regarding to the dnn installation its came because of the Frame work 4.0 syncronization with the IIS the orignal post is here http://www.dotnetnuke.com/Community/Forums/tabid/795/forumid/107/threadid/381656/scope/posts/Default.aspx I also past the content here Symptoms Getting the below error while browsing the website running on ASP.NET 4 application pool. Server Error in '/myVDir' Application. -------------------------------------------------------------------------------- Could not load type 'System.ServiceModel.Activation.HttpModule' from assembly 'System.ServiceModel, Version=3.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'. Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.TypeLoadException: ...