Cannot find JavaScriptSerializer in .Net 4.0

Question

I cannot seem to find the JavaScriptSerializer object nor the the System.Web.Script.Serialization namespace within Visual Studio 2010. I need to serialize something to JSON what am I supposed to use?

And yes, I already included the System.Web.Extensions (in System.Web.Extensions.dll) within the project. Which is why I am shocked?

I do know System.Web.Extensions was marked as obsolete in 3.5

I have the same problem, and I gotta say the answers are pretty useless. I am targeting the ".NET Framework 4", not ".NET 4 Client Profile". I have referenced the System.Web.Extensions assembly. But when I try using the System.Web.Script.Serialization namespace, VS 2010 tells me "The type or namespace Script does not exist in the namespace System.Web". Has anyone found a real solution for this? I'm stumped! — twakjaco
– twakjaco, Commented Nov 16, 2011 at 18:28

Nico Schertler · Accepted Answer · 2017-09-19 17:58:00Z

545

Check if you included the .net 4 version of System.Web.Extensions - there's a 3.5 version as well, but I don't think that one works.

These steps work for me:

Create a new console application
Change the target to .net 4 instead of Client Profile
Add a reference to System.Web.Extensions (4.0)
Have access to JavaScriptSerializer in Program.cs now :-)

edited Sep 19, 2017 at 17:58

Nico Schertler

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answered Nov 25, 2011 at 6:20

Steffen

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1 Comment

zokaee hamid Over a year ago

in vb.net don't forget "new" and ( ) like : Dim JsonConvert As New JavaScriptSerializer()

Scott Johnson · Accepted Answer · 2013-03-13 16:44:23Z

141

Right click References and do Add Reference, then from Assemblies->Framework select System.Web.Extensions.
Now you should be able to add the following to your class file:

    using System.Web.Script.Serialization;

answered Mar 13, 2013 at 16:44

Scott Johnson

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Comments

Community · Accepted Answer · 2020-06-20 09:12:55Z

43

From the first search result on google:

http://msdn.microsoft.com/en-us/library/system.web.script.serialization.javascriptserializer.aspx

JavaScriptSerializer Class

Provides serialization and deserialization functionality for AJAX-enabled applications.

Inheritance Hierarchy

System.Object

System.Web.Script.Serialization.JavaScriptSerializer

Namespace: System.Web.Script.Serialization

Assembly: System.Web.Extensions (in System.Web.Extensions.dll)

So, include System.Web.Extensions.dll as a reference.

edited Jun 20, 2020 at 9:12

CommunityBot

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answered Aug 9, 2011 at 18:18

Paul

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1 Comment

neminem Over a year ago

Two years later, on a totally unrelated project: it also helps if you capitalize it correctly >.> (it's not JavascriptSerializer).

Tom Stickel · Accepted Answer · 2019-05-28 16:31:41Z

32

I'm using Visual Studio 2015 and finally ran across this post.

Yes in order to use

JavaScriptSerializer json = new JavaScriptSerializer();

You must right click on references and under Assemblies --> Framework choose

System.Web.Extensions

Then add in your reference

using System.Web.Script.Serialization;

edited May 28, 2019 at 16:31

answered Sep 17, 2015 at 0:44

Tom Stickel

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Comments

Gonzalo.- · Accepted Answer · 2012-09-26 17:24:21Z

14

This is how to get JavaScriptSerializer available in your application, targetting .NET 4.0 (full)

using System.Web.Script.Serialization;

This should allow you to create a new JavaScriptSerializer object!

edited Sep 26, 2012 at 17:24

Gonzalo.-

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answered Aug 28, 2012 at 8:33

Alex Hopkins

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1 Comment

KansaiRobot Over a year ago

Script does not exist

Ema.H · Accepted Answer · 2017-02-07 13:25:53Z

13

using System.Web.Script.Serialization;

is in assembly : System.Web.Extensions (System.Web.Extensions.dll)

edited Feb 7, 2017 at 13:25

answered Jan 20, 2014 at 9:45

Ema.H

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Comments

Christopher Currens · Accepted Answer · 2011-08-09 18:18:45Z

9

Are you targeting the .NET 4 framework or the .NET 4 Client Profile?

If you're targeting the latter, you won't find that class. You also may be missing a reference, likely to an extensions dll.

answered Aug 9, 2011 at 18:18

Christopher Currens

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3 Comments

Prisoner ZERO Over a year ago

.NET Framework 4. And I already have 'System.Web.Extensions' included in the project

Christopher Currens Over a year ago

Is this a project you've upgraded from an earlier version of .net?

user1003221 Over a year ago

I'm having this issue with a project I upgraded. It doesn't appear to be resolved by using the original .net version (3.5) though...

jltrem · Accepted Answer · 2013-05-02 22:58:15Z

For those who seem to be following the answers above but still have the problem (e.g., see the first comment on the poster's question):

You are probably working in a solution with many projects. The project you appear to be working in references other projects, but you are actually modifying a file from one of the other projects. For example:

project A references System.Web.Extensions
project A references project B

But if the file you are modifying to use System.Web.Script.Serialization is in project B, then you will need to add a reference to System.Web.Extension in project B as well.

David Ly · Accepted Answer · 2011-08-09 18:18:59Z

8

Did you include a reference to System.Web.Extensions? If you click on your first link it says which assembly it's in.

answered Aug 9, 2011 at 18:18

David Ly

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1 Comment

David Ly Over a year ago

In that case maybe check out @Christopher's answer.

riahc3 · Accepted Answer · 2013-02-21 15:51:15Z

5

You have to add the reference to the project.

In Assemblies, there is a System.Web.Extensions Add that.

Once that is done put:

    using System.Web;
    using System.Web.Script;
    using System.Web.Script.Serialization;

That worked for me.

answered Feb 21, 2013 at 15:51

riahc3

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Iztoksson · Accepted Answer · 2019-02-20 14:16:49Z

5

You can use another option which is the Newtonsoft.Json, you can install it from NuGet Package Manager.

Tools >> Nuget Package Manager >> Package Manager Console by issuing command

Install-Package Newtonsoft.Json

or

by using the GUI at Tools >> Nuget Package Manager >> Manage NuGet Packages for Solution...

edited Feb 20, 2019 at 14:16

Iztoksson

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answered Jun 16, 2017 at 14:18

Alexander Zaldostanov

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1 Comment

Brian Over a year ago

Note that this is Microsoft's documented recommendation. On .Net Core, Microsoft no longer even offers JavaScriptSerializer (nor the rest of System.Web.Extensions).

Milan · Accepted Answer · 2015-10-29 22:42:42Z

4

Just so you know, I am using Visual Studio 2013 and have had the same problem until I used the Project Properties to switch to 3.5 framework and back to 4.5. This for some reason registered the .dll properly and I could use the System.Web.Extensions.

answered Oct 29, 2015 at 22:42

Milan

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