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, Nov 16 '11 at 18:28
Related post [here](https://stackoverflow.com/q/1156313/465053). — RBT, Nov 12 '17 at 01:17

score 543 · Accepted Answer · edited Sep 19 '17 at 17:58

543

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 '17 at 17:58

Nico Schertler

32,049
4
39
70

answered Nov 25 '11 at 06:20

Steffen

13,648
7
57
67

in vb.net don't forget "new" and ( ) like : Dim JsonConvert As New JavaScriptSerializer() – zokaee hamid Nov 06 '19 at 13:02

score 140 · Answer 2 · answered Mar 13 '13 at 16:44

140

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 '13 at 16:44

Scott Johnson

1,500
1
9
4

score 43 · Answer 3 · edited Jun 20 '20 at 09:12

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 '20 at 09:12

Community

1
1

answered Aug 09 '11 at 18:18

Paul

4,422
5
29
55

3

Two years later, on a totally unrelated project: it also helps if you capitalize it correctly >.> (it's not JavascriptSerializer). – neminem Mar 04 '15 at 22:49

Tom Stickel · Answer 4 · 2019-05-28T16:31:41.207

30

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 '19 at 16:31

answered Sep 17 '15 at 00:44

Tom Stickel

19,633
6
111
113

score 15 · Answer 5 · edited Sep 26 '12 at 17:24

15

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 '12 at 17:24

Gonzalo.-

12,512
5
50
82

answered Aug 28 '12 at 08:33

Alex Hopkins

872
9
11

2

Script does not exist – KansaiRobot May 25 '18 at 07:09

Ema.H · Answer 6 · 2017-02-07T13:25:53.407

13

using System.Web.Script.Serialization;

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

edited Feb 07 '17 at 13:25

answered Jan 20 '14 at 09:45

Ema.H

2,862
3
28
41

score 9 · Answer 7 · answered May 02 '13 at 22:58

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.

score 9 · Answer 8 · answered Aug 09 '11 at 18:18

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 09 '11 at 18:18

Christopher Currens

29,917
5
57
77

.NET Framework 4. And I already have 'System.Web.Extensions' included in the project – Prisoner ZERO Aug 09 '11 at 18:24
Is this a project you've upgraded from an earlier version of .net? – Christopher Currens Aug 09 '11 at 18:33
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... – user1003221 Oct 01 '12 at 13:40

score 8 · Answer 9 · answered Aug 09 '11 at 18:18

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 09 '11 at 18:18

Davy8

30,868
25
115
173

In that case maybe check out @Christopher's answer. – Davy8 Aug 09 '11 at 18:24

score 5 · Answer 10 · answered Feb 21 '13 at 15:51

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 '13 at 15:51

riahc3

857
4
10
23

score 5 · Answer 11 · edited Feb 20 '19 at 14:16

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 '19 at 14:16

Iztoksson

980
16
32

answered Jun 16 '17 at 14:18

Alexander Zaldostanov

2,907
4
30
39

1

Note that this is Microsoft's [documented recommendation](https://learn.microsoft.com/en-us/dotnet/api/system.web.script.serialization.javascriptserializer). On .Net Core, Microsoft no longer even offers JavaScriptSerializer (nor the rest of System.Web.Extensions). – Brian Mar 05 '18 at 16:46

score 3 · Answer 12 · answered Oct 29 '15 at 22:42

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.

Cannot find JavaScriptSerializer in .Net 4.0

12 Answers12

Linked