This post is about an unusual configuration issue that, many Umbraco developers face when they first try to upgrade their Umbraco installation to .Net Framework 4.0. It is unusual in a sense that over the last few framework releases there has been a norm that the web.config schemas were backward compatible and it was never required to update the configurations during an upgrade.
.Net Framework 4.0 has been launched with a new machine.config file, and off course it doesn't override the earlier machine.config in use by previous frameworks. The following changes have been done in the new machine.config:
- ASP .NET Tag Sections
- ASP .NET AJAX
- ASP .NET Dynamic Data
- ASP .NET Routing
- ASP .NET Chart Control
So, we will need to omit all the above mentioned items form our web.config, so that Umbraco starts working with .Net Framework 4.0.
- Set the web site's Application Pool to ASP.NET v4.0.
- Remove/Comment the sectionGroup named "system.web.extensions" under configSections tag.
- Change the compilation tag and set the targetFramework attribute to 4.0
<compilation defaultLanguage="c#" debug="true" batch="false" targetFramework="4.0"> - Delete the whole assemblies section below that compilation tag.
- Remove/Comment the controls having "asp" tagPrefix, under system.web/pages/controls tag.
- Remove/Comment all handlers and modules specific to "ASPNETAJAX", under system.webServer and system.web tags.
- Most importantly, search for "Version=3.5.0.0" text in you web.config and replace it with "Version=4.0.0.0".
- Finally, make sure you have the "Microsoft.Scripting.ExtensionAttribute.dll" in Umbraco bin directory, i.e. most probably at "c:\inetpub\wwwroot\bin".
That's all folks, enjoy Umbraco development on .Net Framework 4.0.
