asp.net Compilation Error (mysql.data)

i have an error when trying to start default.aspx.

Compiler Error Message: CS0433: The type 'MySql.Data.MySqlClient.MySqlConnection' exists in both 
'c:\Windows\assembly\GAC_MSIL\MySql.Data\6.3.6.0__c5687fc88969c44d\MySql.Data.dll' and 'c:\Windows\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files\elwazefa\fd12d8de\3446c68c\a开发者_如何学编程ssembly`\dl3\dc121b8b\00d6e0c3_62aacb01\MySql.Data.CF.DLL'`

i am using asp.net 3.5 what is the problem, thanks

It looks to me like you have references to both the Compact Framework and the standard framework MySQL libraries in your project. You need to remove the references to the ones that have .CF in their filename.

Check your web.config file assemblies section for multiple references:

<compilation>
  <assemblies>
    ...             
  </assemblies>
</compilation>

If there is more than one then remove it (the one not in the GAC, I would say off-hand.)

Also, as @Abe suggests, delete the temporary files under the following path:

c:\Windows\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files\