Asp.net Ajax Error

Question

I added the ModalPopupExtender to an existing ASP.NET application. At runtime I get the following error

Compilation Error Description: An error occurred during the compilation of a resource required to service this request. Please review the following specific error details and modify your source code appropriately.

Compiler Error Message: BC32206: Indirect reference is being made to assembly System.Web.Extensions version 3.5.0.0, which contains 'AjaxControlToolkit.ModalPopupExtender'. This Project references a prior version of System.Web.Extensions version 1.0.61025.0. To use 'AjaxControlToolkit.ModalPopupExtender', you must replace the reference to System.Web.Extensions with version 3.5.0.0 or higher.

Source Error:

Line 29:
Line 30:
Line 31:

How do I fix this.

Answer 1

You're trying to compile a .NET 3.5 application with a reference to a .NET 1.1 module. Make sure you have the .NET 3.5 framework installed, and if you do, make sure you're trying to build it in .NET 3.5.

You may also want to see this post.

Answer 2

Are you sure you have the correct version of the AjaxControlToolkit? There is a version that is compiled against .NET 3.5 and one that is against .NET 2.0.

It looks like you are still in 2.0 land (with the 2.0 AJAX extensions). If so, get the correct version of the Toolkit. It looks like the latest version does not support .NET2.0.

If you are in 3.5 land, look at your references for System.Web.Extensions and make sure you are referencing the .NET3.5 version (actual version 3.5.x which is "built in"), not the .NET2.0 version (actual version 1.0.x, which is a download addition).