When preparing to migrate to Project Online and Project Server 2016, if you are using the old Project Server Interface (PSI) you may have some work to do as some core aspects of the PSI will no longer exist.
According to the blog from the Project team “A unified scheduling engine and API in Project Online and Project Server 2016” (14 July 2015) the PSI is no longer just depreciated, but is gradually being gutted. The replacement will be the client side object model (CSOM) and Project Calculation Service (PCS).
The PSI will still exist for the near future. However, the core Project class of the PSI will be removed. If your PSI code does not utilize SOAP calls to interact with Projects then it may still be OK, for now at least.
If you would like to discuss potential solutions, please get in contact with us today.