BONUS TIP! Configuring IIS After Installing .NET Framework 2.0 Beta 1

Posted Monday, December 6, 2004 11:38 AM by C-Dog's .NET Tip of the Day
Most people have experienced this by now, but I am going to go ahead and document it.  After installing the .NET Framework 2.0 Beta 1, all of your web applications are configured to run using version 2.0 of the framework.  When you try to run any of your existing 1.1 applications using a browser, more often than not you are going to get a yellow screen, or a server application unavailable error message.  If you have event logging turned on, you will probably either see a message elaborating more on the above or one of your controls might give you an error like "DataSource and DataSourceId are both defined on this control.".
For the most part, this is easy to fix.  Simply tell your web applications to run using ASP.NET 1.1 again.  In the past you usually just used aspnet_regiis -i out of the v1.1 folder.  However, ASP.NET 2.0 added a new ASP.NET tab in IIS on your web site's properties.  Simply, click on the tab and choose v1.1.  You may need to do this on every web instance and web application on your server or machine.
Running multiple versions of the Framework on the same web instance
Some times it may be necessary to run one particular web application inside an instance on a different version of the framework.  Typically how you do this is you create the application in IIS and choose v2.0 on the ASP.NET tab.  However, when you run the application, you get an error.  If you check the event log it will tell you that you can not run two version of the framework inside the same application pool.
To resolve this, open up Application Pools inside IIS and add a new application pool.  Call it something like ASP.NET 2.0 Application Pool.  Then edit the web application that you created and choose the new application pool you created.  Make sure all of the other web applications on the site are using a different application pool (i.e.: Default Application Pool). 
At this point, it almost always requires a restart of IIS.  Once you do that, all of your applications should run.

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