Everything I have done today is gone. 2 hours of work is ruined!
All saved Cubase projects says:
"Project “xxx.cpr” was created with Cubase 1.x.
This program version cannot load it. " Whatta hell now?
Cubase, Monterey, plugins all latest version.
No information, no help.
What do you need?
What Cubase version are you using ? I guess that it’s a recent one. At first glance, I would try to install SX3, then load and save the project again with it. Normally, it then should be usable by all the Cubase versions that were published after : see here, for more details…
But what is strange, though, is that normally a SX1 .cpr project file should be directly compatible with SX3 and further versions, contrarily to an .arr one. So, still something to try, I think, but without being sure of a successful result…
Yes. all SW versions are current. I added to my profile.
Strange problem indeed. How Cubase 12.0.40 can even save file that itself can not open is mystery.
I first thought its all gone, but I remembered all I had done in few hours and I quickly got back up to speed from yesterdays song version.
Good idea to try SX!
Thank you very much cubic13
Glad that you got it sorted, somehow…
Additionaly, I would be sure to save the involved projects with a slightly different name to force Cubase to create new .cpr files, which will surely be compatible, unless there is a mysterious voodoo process going on…
Yes. That is how I have been saving project versions since SX days. That’s good advice when working with Cubase.
This means that your project is corrupted. Cubase can see that it’s a supposedly valid .cpr file, but it can’t load it.
This is not going to help. Cubase SX wont be able to load it either.
Point taken : his project is corrupted and I can just hope that @Takkyi has a safe backup of it somewhere.
I would like you to note that I did a warning about my own suggestion, though. Maybe you haven’t read it until its end, so, I invite you to read it again…
There is a menu entry and a key command (Strg+Alt+S) available to save a current project as a new version, and Cubase/Nuendo adds a two-digit number at the end.
So you have a basic version control at hand.
Yep. It’s another way to do so… 
Thanks for everyone. I got it sorted. I restored from Time Machine backup and rest from my head 
Something went bonkers in Cubase. From start of the day all saved versions including .bak files was corrupted. I noticed that after Cubase just disappeared without any crash logs and I tried to start project again.
This kind of things erodes trust for Cubase. That nagging feeling, if this gonna happend again… I prefer and like very much Cubase way of workflow over LogicProX even Im fluent with it.
I had this issue using Cubase 12 when trying to open my project files from Cubase 5. If you backup your older version of Cubase projects it should save them with a .bak file extension. Your newer version of Cubase should be able to open these files. If there are any Plugins unavailable, it will prompt you and you can see what is missing.
Why? What does that do?
It backs up the project and allows you to open the project in newer versions of Cubase. You can just use File / Back Up Project to save it as *.bak and then open it in your latest version of Cubase
No, this is not how it works. Doing this does not backup the project with its media, and it’s unnecessary. Cubase can open *cpr and *npr projects from previous versions. It can also open .bak files.
Only Auto Save saves .bak files.
The Project backup function is something else.