In this article we will be seeing how to resolve the error "Could not load type
'System.Data.Services.Providers.IDataServiceUpdateProvider' from assembly
'System.Data.Services, Version=3.5.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'".
Error:
When you try to access the SharePoint list using REST API through the URL
http://servername:12345/_vti_bin/listdata.svc you may be getting the following
error.

Reason:
The reason for the error would be you may not have installed ADO.Net Data
Services in your computer server.
ADO.Net Data Services:
- For Windows Vista and Windows 2008 - http://www.microsoft.com/downloads/details.aspx?familyid=4B710B89-8576-46CF-A4BF-331A9306D555&displaylang=en
- For Windows 7 and Windows 2008 R2 - http://www.microsoft.com/downloads/details.aspx?familyid=79d7f6f8-d6e9-4b8c-8640-17f89452148e&displaylang=en
Note: Download the files appropriate to you or else when you try to install you would be getting the following error.

Windows 2008 R2:
For Windows 2008 R2 select the following one

Install ADO.Net Data Services:
- Open the downloaded file.

- Windows Update Standalone Installer wizard
will pop up.

- Click on Yes.

- Restart your server.
- Now try to access the list using API, you would be able to access the list successfully.

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