11231 : Script manager is ambiguous in the namespace system.Web.UI

Question

I went into vb.net5 and started a new web site and tied doing the instructions for To create an ajax< ?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

enabled Gantt chart. The error is Script manager is ambiguous in the namespace system.Web.UI.

 

After this I tried adding it to my current  ajax aspx vb.net 2005 and got the same errors.  And can’t get the old versions in source safe.  The error is Script manager is ambiguous in the namespace system.Web.UI.  I think something got messed up in the .net framework or something.  Don’t know how to fix this.

Answer

My guess is that your web.config is messed up.

 

Best solution?

 

Create a new project drag an update panel to it (with the VS and ajax version you want).

Copy the content from that web.config to your actual project.

 

 

More details:

Maybe you have a row like this:

<add assembly=”System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35″/>

 

And a row like this:

<add assembly=”System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35″/>

 

In the web.config? Then VS does not know where to go for system.web.extensions…