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?
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...
You're probably targeting the Client Profile, in which System.Web.dll is not available.
You can target the full framework in Project Properties.
You need to add the System.Web reference;
- Right click the "Reference" in the Solution Explorer
- Choose "Add Reference"
- Check the ".NET" tab is selected.
- Search for, and add "System.Web".
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.
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..
After following the answers above , and did
Project -> Properties -> Application -> Target Framework -> select ".Net Framework 4"
It still didn't work until I went to Project -> Add Reference
And selected System.web.
And everything worked link a charm.
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.
Agrega System.web a las referencias del proyecto.
[Edit]
According to Google Translate, this translates to:
Add System.Web to the project references.
I had the same problem what I did, I copied web.dll from Microsoft.NET framework, then paste in root of project, then add dll refrence to app, it worked
It worked for by following process:
Add Reference:
system.net
system.web
also, include the namespace
using system.net
using system.web
Adding a reference to Sysem.Web.Dll did it for me.
来源：https://stackoverflow.com/questions/2405182/httputility-does-not-exist-in-the-current-context