A hotfix is now available for issues most commonly described as " Controls are not being recognized in the code-behind " and " Editing existing .aspx regenerates .aspx.designer.(cs), but most of the controls are now missing ”. This hotfix can be downloaded from: http://connect.microsoft.com/VisualStudio/Downloads/DownloadDetails.aspx?DownloadID=27117 The update addresses the following Connect bugs: http://connect.microsoft.com/VisualStudio/feedback/ViewFeedback.aspx?FeedbackID=532641 : Cannot embed standard asp.net controls in Ajax Control Toolkit TabContainer http://connect.microsoft.com/VisualStudio/feedback/ViewFeedback.aspx?FeedbackID=533071 : Controls in CreateUserWizard WizardStep not visible as before http://connect.microsoft…(read more)