SharePoint: Could not load type ‘System.Data.Services.Providers.IDataServiceUpdateProvider’ from assembly ‘System.Data.Services, Version=3.5.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089′.

Our application had a control which used REST API to get list items. The control was working fine until the QA tested it on one of the VMs where it did not return any results. On further investigation we found that if we directly run the REST query from the Url we were getting following error:
Could not load type ‘System.Data.Services.Providers.IDataServiceUpdateProvider’ from assembly ‘System.Data.Services, Version=3.5.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089′.
To fix this issue we ended up installing ADO.NET Data Services Update for .NET Framework 3.5 SP1 for Windows 7 and Windows Server 2008 R2 from here.
profile for Nadeem Yousuf at SharePoint Stack Exchange, Q&A for SharePoint enthusiasts

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