Every so often, especially when setting up a new virtual machine, at some point I get this error when working in SSIS:
It happens often enough that, to be honest, I mostly wanted to make this as a record to myself and friends, but I am hopeful that you will be helped as well. And to give credit where it is due, I found the original answer at Stack Exchange:
The steps are pretty straight forward.
1. First, if you have Visual Studio open, close it.
2. In the classic Windows menu go to Start, All Programs, Microsoft Visual Studio 2012, Visual Studio Tools, and right click on the “Developer Command Prompt for VS2012” and pick “Run as administrator”. If you are in Windows 8 or Server 2012 or later, probably easiest to just do a search for “Developer Command Prompt for VS2012”.
3. Navigate to Visual Studio’s Private Assemblies folder by entering “CD C:\Program Files (x86)\Microsoft Visual Studio 11.0\Common7\IDE\PrivateAssemblies” (If you have installed VS to another drive or folder, adjust the path accordingly).
4. Enter the command “gacutil /if Microsoft.SqlServer.Dts.Design.dll” into the command prompt.
Now you should be able to open your SSIS projects.
The dll is the main set of libraries for SQL Server Integration Services. For some reason, after certain Windows updates, this becomes deregistered and you have to manually add it back. Not a huge deal, but annoying if it happens often enough. As I just had it happen today after a Windows update to the Hyper-V VM I use for some of my SQL Server development, I wanted to post this as a reminder on how to correctly fix the issue.