I have 2 different tfs server setup , one runs with tfs 2015 other with tfs 2017. I need to move a specific project from 2015 to the 2017 instance. Please guide me with the best approach that we can go with...
You could not directly move things based on team project level , this seems like an inherent design issue with the source and work item entities. Since there is also not able to move a Team Project between Team Project Collections, there has been a uservoice:
Make it possible to move a Team Project between Team Project Collections
You have to move the entire team project collection if you want to keep all workitems, source control history for that specific project. If you just want code, the simplest way is copy them and add it in a newly created team project in TFS2017.