Dynamics 365 (CRM) Unknown Report Version: 9.0 problem

Just a quick post on a nasty problem that caused me some grief, and my solution to fix it.
I am using Visual Studio 2017 with the recently released Dynamics 365 Report Authoring Extension. I wanted to customize the Dynamics 365 (aka CRM Online) Invoice report, so I went to the reports and downloaded the Invoice and Invoice Sub-Report RDL files. I knew that these reports would have SQL queries so I quickly set up a VS 2017 BIDS report project, and put the RDL files in there. I spent some time converting the SQL to FetchXML, and when I tried to save it, got the error message "Unknown Report Version: 9.0" and could not save the project.

I read several blogs that suggested manually tweaking the RDL source code and tried a few of those but it just caused more problems. I read that someone had a similar problem with RDLC files and they used VS 2015 to open and then save the original files before opening them in VS 2017, so I tried going back to one of my old VS 2012 environments where I had BIDS installed, opened and saved the RDL files in there, and them moved them to my 2017 development environment, and I now I can make my changes and save the work.

Please note, if this is your first time creating D365 reports with VS  2017, be aware that the RDL file you start with is not what you will publish to CRM. You must build your report project, then navigate to the Bin folder under your project and get the RDL files from there to publish in D365. The reason is that the report Project allows you to target different versions of SQL server.