Could not load file or assembly 'msddsp, Version=9.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'

Issue:-

when we double click on the Maintenance plans to modify or Execute, under Management --> Mainteance Plans. We get below error. 

Could not load file or assembly 'msddsp, Version=9.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' or one of its dependencies. The system cannot find the file specified. (Microsoft.DataTransformationServices.Design)

In order to resolve this error...

In your existing envirnment, copy this Folder from Any good Server, the source server from where you are getting this file should have same version of Windows + SQL Server. 

Copy MSDesigners8 folder to
..\Program Files (x86)\Common Files\Microsoft Shared\MSDesigners8
\Resources 

• msdds.dll 
• msddsf.dll 
• msddslm.dll 
• msddslmp.dll 
• msddsp.dll 

2. Register following DLLs with RegSvr32

• msdds.dll 
• msddsf.dll 
• msddslm.dll 

3. Import following .NET assemblies 

• msddslmp.dll 
• msddsp.dll 

It actually works just dragging it and drop to ..\Windows\Assemblies 

If the above does not work:

Go to the source server to below path:

C:\windows\assembly\GAC_MSIL

Copy folders “msddslmp.dll” and “msddsp.dll” to “C:\windows\assembly\GAC_MSIL” path of target server.

your issue will get resolved. 

Thanks for Reading..