Reference Microsoft.SqlServer.Smo.dll

For those who need the sql server 2014 version (version 120) you need to download and install the following packages from Microsoft:

• SQLSysClrTypes (x64): https://download.microsoft.com/download/1/3/0/13089488-91FC-4E22-AD68-5BE58BD5C014/ENU/x64/SQLSysClrTypes.msi
• SharedManagementObjects(x64): https://download.microsoft.com/download/1/3/0/13089488-91FC-4E22-AD68-5BE58BD5C014/ENU/x64/SharedManagementObjects.msi

You can find all relevant info on Microsoft website on this page (as suggested correctly by @mitch-wheat ): https://www.microsoft.com/en-gb/download/details.aspx?id=42295

I know this is an old question, but I just ran into the same issue. @Mitch_Wheat is correct that as a minimum you need references to the 4 SMO assemblies. Trying to add all 4 at once, however, gave me the error you listed.

Adding the assemblies one at a time bypassed the error.

You can try this unofficial nuget package...

https://www.nuget.org/packages/Unofficial.Microsoft.SQLServer.SMO/

Install-Package Unofficial.Microsoft.SQLServer.SMO

C:\Program Files\Microsoft SQL Server\100\SDK\Assemblies is the correct folder location (or C:\Program Files (x86)\Microsoft SQL Server\100\SDK\Assemblies on 64-bit systems).

You need to add references to:

• Microsoft.SqlServer.ConnectionInfo.dll

• Microsoft.SqlServer.Smo.dll

• Microsoft.SqlServer.Management.Sdk.Sfc.dll

• Microsoft.SqlServer.SqlEnum.dll

(These are the minimum files that are required to build an SMO application)

For SQL Server 2016, this location is C:\Program Files (x86)\Microsoft SQL Server\130\SDK\Assemblies (for the 64bit version).

Ref.: How to: Create a Visual C# SMO Project in Visual Studio .NET

The SQL Server Management Objects (SMO) are downloadable as part of the relevant SQL Server (20XX) Feature Pack (check the smallprint as I don't believe these are redistributable?)