Cubase Pro 11 creates a new project from a “newer version”, then can’t open it.
Beautiful.
There was actually no Cubase version with the name Cubase 1 and the file extension *.cpr.
Possibly Cubase SX is meant 
The earliest version of Cubase that can be installed under Win10 is Cubase SX3.1. I have this version on my PC and can even use it to open ancient * .all songs that I once created on the Atari.
You can download the installation medium here:
Converting Cubase VST songs (ALL/ARR) into CPR format – Steinberg Support
Back to your question: It is possible that your cpr file is corrupt?
There was a similar case with such an error message some time ago.
Edit: Have a look:
Search results for ‘"Cubase 1.x"’ - Steinberg Forums
There was in fact a Cubase SE 1 which had the final version 1.0.7 and was to Cubase SX what Elements is now to Cubase Pro. IIRC it was the first version to ship as a freebie with Zoom hardware, and I think as part of a package called “Studiocase” – maybe around 2004?
I should be possible (as P.A.T. suggests) to load these projects with SX3, save them under a different name, and then load them into Cubase 11.