When working in ASP.NET you may wish to change from version 2.0 to 4.0. You can do this directly from your 123-reg Hosting control panel.
This article will explain how to select the new version of ASP.net 4.0.
Scroll down to the Web Hosting section, select the relevant domain name from the drop-down box and click on the Manage button.
Click on the Manage IIS Application Pools link in the Web Tools section./p>
Select the version of ASP.NET using the drop down list in the Application Pool Managed Runtime Version section and click on the Update Now to save the change.
Please Note: We recommend that you back up your website files prior to upgrading from version 2.0 v to 4.0.