HttpUtility does not exist in the current context

Question

I get this error when compiling a C# application. Looks like a trivial error, but I can't get around it.

My setup is Windows 7 64 bit. Visual-Studio 2010 C# express B2Rel.

I added a reference to System.Web.dll located at C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.0, but it has a yellow exclamation symbol and I still get the above error. I also have the using System.Web declaration.

What am I doing wrong?

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Update: After getting the prompt answer pointing me at the root cause, I searched a bit in Google to where it states that System.Web.dll is for the full framework. I did not find such a reference.
For newbies like me, this blog summarizes the difference between the frameworks (client and full) nicely. I could not find a spot that says whether a certain Dll is supported in the client framework or not. I guess the exclamation mark in Visual Studio should be the first signal...

Answer 1

You need to add the System.Web reference;

1. Right click the "Reference" in the Solution Explorer
2. Choose "Add Reference"
3. Check the ".NET" tab is selected.
4. Search for, and add "System.Web".

Answer 2

You're probably targeting the Client Profile, in which System.Web.dll is not available.

You can target the full framework in project's Properties.

Answer 3

SLaks has the right answer... but let me be a bit more specific for people, like me, who are annoyed by this and can't find it right away :

Project -> Properties -> Application -> Target Framework -> select ".Net Framework 4"

the project will then save and reload.

Answer 4

In order to resolve this, Kindly go to the below path

Project-->Properties-->Application-->TargetFramework

and change the Framework to ".NET Framework 4".

Once you do this, the project will close and re-open.

This should solve the error

(but for some reason @Karan Modi's answer does not...)

next right-click the references tab in the solution explorer and choose add reference,

choose "System.Web"

(declaring the namespace directly by "using System.Web;" doesnt seems to be enough...you have to add it to the solution explorer...i cant understand why - which is no surprise because i am a cobol programmer..