The main problem is that an “ERD file” (the erd extension) doesn’t really tell us much useful about the file format. I looked up the XRM toolbox as well as its software repository and that brings me to another question: which plugins (extensions) are you using that allow you to save ERD files?
Note that I don’t have experience with MS Dynamics but I am trying to get enough information which might help to find a solution…
Correct me if I’m wrong please: if I understand correctly you use the XrmToolbox to connect to your Dynamics 365 environment (which is hosted in the cloud) and you then extract data from it. You use a plugin for XrmToolbox which can visualize this data as an ERD diagram, which you then save as an .erd file.
As such my question: what plugin? Would that be Chart manager by any chance?
Because that would be something that some of us might be able to use. I already checked out their GitHub repository, discovered that it was (most likely) set up with Visual Studio (I conclude as much from a so called “solution file” (*.sln) which I found) but I get tons of errors because I’m missing SDK’s (development kits; in order to program against a program you need an API of some sort to work with).
So I fired up VS Code instead and I think I already discovered the routine which loads / imports the data:
No promises, and definitely no guarantees, but this might give us a clue about the file format. And once you know the file format then you have a much better chance of determining if the data can be imported or converted somehow.