<div>
Please check whether your project references both assemblies.
</div>


Please check whether your project references both assemblies.

<div>
I have added this System.Web.Extensions.dll &nbsp;dll files externally. Not through add reference. Because there is different version(higher) there. So i have added manually into bin folder. &nbsp;Please attached the screenshot<br />
<a href="https://filedb.experts-exchange.com/incoming/2011/11_w45/518505/DLL-Versions.png" target="_blank" class="file-inline" title="Reference DLL Version screen shot (112 KB)"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512"><path d="M67.508 468.467c-58.005-58.013-58.016-151.92 0-209.943l225.011-225.04c44.643-44.645 117.279-44.645 161.92 0 44.743 44.749 44.753 117.186 0 161.944l-189.465 189.49c-31.41 31.413-82.518 31.412-113.926.001-31.479-31.482-31.49-82.453 0-113.944L311.51 110.491c4.687-4.687 12.286-4.687 16.972 0l16.967 16.971c4.685 4.686 4.685 12.283 0 16.969L184.983 304.917c-12.724 12.724-12.73 33.328 0 46.058 12.696 12.697 33.356 12.699 46.054-.001l189.465-189.489c25.987-25.989 25.994-68.06.001-94.056-25.931-25.934-68.119-25.932-94.049 0l-225.01 225.039c-39.249 39.252-39.258 102.795-.001 142.057 39.285 39.29 102.885 39.287 142.162-.028A739446.174 739446.174 0 0 1 439.497 238.49c4.686-4.687 12.282-4.684 16.969.004l16.967 16.971c4.685 4.686 4.689 12.279.004 16.965a755654.128 755654.128 0 0 0-195.881 195.996c-58.034 58.092-152.004 58.093-210.048.041z"/></svg>DLL-Versions.png</a>
</div>


I have added this System.Web.Extensions.dll  dll files externally. Not through add reference. Because there is different version(higher) there. So i have added manually into bin folder.  Please attached the screenshot
DLL-Versions.png [https://filedb.experts-exchange.com/incoming/2011/11_w45/518505/DLL-Versions.png]

DLL-Versions.png

<div>
<div class="content wysiwyg-content">
Hi,<br />
<br />
I have installed both vs 2010(.net4.0) and vs 2005(.net2.0).<br />
.net 4.0 working correctly. When &nbsp;i build the .net 2.0 projects gets error below.<br />
<br />
First installed .net4.0(vs2010) then installed .net 2.0(vs 2k5)<br />
<br />
The type 'System.Web.Script.Service<wbr />s.ScriptMe<wbr />thodAttrib<wbr />ute' exists in both <br />
'c:\Windows\Microsoft.NET\<wbr />Framework\<wbr />v2.0.50727<wbr />\Temporary<wbr /> ASP.NET Files\projectking.web\5437<wbr />aa02\ea21b<wbr />cc0\assemb<wbr />ly\dl3\762<wbr />85535\0045<wbr />f8b2_18dcc<wbr />801\System<wbr />.Web.Exten<wbr />sions.DLL'<wbr /> <br />
and 'c:\Windows\assembly\GAC_M<wbr />SIL\System<wbr />.Web.Exten<wbr />sions\3.5.<wbr />0.0__31bf3<wbr />856ad364e3<wbr />5\System.W<wbr />eb.Extensi<wbr />ons.dll' &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br />
<br />
<a href="https://filedb.experts-exchange.com/incoming/2011/10_w45/518491/Ambi-DLL-Version.png" target="_blank" class="file-inline" title="Ambiguous DLL with different versions (194 KB)"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512"><path d="M67.508 468.467c-58.005-58.013-58.016-151.92 0-209.943l225.011-225.04c44.643-44.645 117.279-44.645 161.92 0 44.743 44.749 44.753 117.186 0 161.944l-189.465 189.49c-31.41 31.413-82.518 31.412-113.926.001-31.479-31.482-31.49-82.453 0-113.944L311.51 110.491c4.687-4.687 12.286-4.687 16.972 0l16.967 16.971c4.685 4.686 4.685 12.283 0 16.969L184.983 304.917c-12.724 12.724-12.73 33.328 0 46.058 12.696 12.697 33.356 12.699 46.054-.001l189.465-189.489c25.987-25.989 25.994-68.06.001-94.056-25.931-25.934-68.119-25.932-94.049 0l-225.01 225.039c-39.249 39.252-39.258 102.795-.001 142.057 39.285 39.29 102.885 39.287 142.162-.028A739446.174 739446.174 0 0 1 439.497 238.49c4.686-4.687 12.282-4.684 16.969.004l16.967 16.971c4.685 4.686 4.689 12.279.004 16.965a755654.128 755654.128 0 0 0-195.881 195.996c-58.034 58.092-152.004 58.093-210.048.041z"/></svg>Ambi-DLL-Version.png</a>
</div>
</div>


Ambi-DLL-Version.png

Hi,

I have installed both vs 2010(.net4.0) and vs 2005(.net2.0).
.net 4.0 working correctly. When  i build the .net 2.0 projects gets error below.

First installed .net4.0(vs2010) then installed .net 2.0(vs 2k5)

The type 'System.Web.Script.Services.ScriptMethodAttribute' exists in both 
'c:\Windows\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files\projectking.web\5437aa02\ea21bcc0\assembly\dl3\76285535\0045f8b2_18dcc801\System.Web.Extensions.DLL' 
and 'c:\Windows\assembly\GAC_MSIL\System.Web.Extensions\3.5.0.0__31bf3856ad364e35\System.Web.Extensions.dll'	


Web.Extensions 3.5 conflicts with 1.0.61025

The successor to Active Server Pages, ASP.NET websites utilize the .NET framework to produce dynamic, data and content-driven web applications and services. ASP.NET code can be written using any .NET supported language. As of 2009, ASP.NET can also apply the Model-View-Controller (MVC) pattern to web applications