New Post: Shared custom functoid in TFS

I misread the error, in TFS it is actually looking in "C:\Program Files (x86)\Microsoft BizTalk Server 2013\Developer Tools\Mapper Extensions". The build server only has the 2010 build components and BTDF 5.0 installed. The developer who created the solution did have BTDF 5.1 installed for a while, but has now gone back to 5.0. Where is that 2013 path found? Is it in a file that can be edited, or replaced with a 5.0 version?

The developer was able to build locally after removing the functoid dll from the Mapper Extensions folder.