I have long used Cubase 11. Now I’'ve purchased 15, but installed it too soon, thinking I could use either version at will. Until I’m comfortable with the new format, I want to continue working on my 11 projects in the 11 format. Many, many Ai suggestions regarding how to have Cubase 11 projects open in 11 haven’t helped., And locating specific sub-folders and one of hundreds of projects by launching 11, then going to “File > Open” takes tremendous time. No ideas as to how to block 15 from opening have worked. I suspect I’ll have to remove 15 from my PC for the time being. Any other ideas?
I’m assuming Windows.
Try right-clicking on a project CPR file and select “Open With…”. If Cubase 11 doesn’t appear on the list, scroll down the list to “More Apps” , if Cubase 11 still isn’t there, scroll down to “Look for another app on this PC”.
Point the open File dialogue to the Cubase 11 executable. (C:\Program Files\Steinberg\Cubase 11\Cubase11.exe)
This should tell Windows to open CPR files in Cubase 11.
This should work as you can normally open different versions of Cubase just fine.
How are you opening C11? Are you double+clicking on the Cubase 11 .exe file and it launches Cubase 15 instead of Cubase 11? Or are you double+clicking on a Project’s .cpr file. I suspect it is the latter because when Windows sees you trying to open a .cpr file it looks to see what program it should use to open it and by default it will use the latest version of Cubase.
If this is what’s happening just launch C11 and use its File Menu (or Hub? don’t recall what version that arrived on) to open the Project File.
I’d be leery of changing the Windows .cpr association to the older version as that would also cause C15 Projects to open in C11 - which will kinda work. I think it’s better to leave the association at its default & launch the desired version directly instead to avoid creating future problems.
Time to take you Duh Pill Mr. G.
Could be a Linux user!
That’s my story and I’m sticking to it!
I’d be careful, too, but it answers the question.
I could also have said there’s an option in the process that allows you to keep the file association.
My opinion - roll up yer sleeves and get stuck in with C15.
Right click one of your Cubase project files .
Select always open with..find and select the Cubase 11 app.
I agree. But it’s not unreasonable to be cautious about such a large jump in versions. Especially when you don’t know exactly what you are jumping into.
I’d recommend the OP take one of their C11 Projects, open in C11 and then do a Save As… and append something like “pre conversion to C15” to the Project name. Keep that as a safety copy. Then close C11 and launch C15. Open the Project in C15 and Save it there which will convert it to a C15 Project. Then roll up the sleeves.
I have one Cubase Projects folder and one Nuendo Projects folder, then each maybe subfoldered into -=Album=- if projects are for a certain album project…I copy and paste my project folders as needed…but the project folders contain all data and info for that project so you can move them anywhere and use File>Open or Open Other or whatever it’s called in the hub. If you can’t be bothered to keep everything in the project folder than Project Backup is your friend 
I have 2, for very different styles of project. But yes, keep your projects in as few locations as possible.
I also never open a project from anywhere except within Cubase.
I agree, especially in a pro environment.
I actually went from Cubase Score 2 (circa 1993-ish) to Cubase Essential 5, in 2010, so I know about big jumps.
At this point, I can launch Cubase 11, go to File > Open, and go through File Explorer to browse through projects, and each will open in 11. But this is much more laborious then my C11 workflow, as I have over 50 uncompleted and yet-to-be-tweaked projects in folders and subfolders with dozens of shortcuts organized on my three screens (piano, organ and orchestra, baroque instrument comps, etc.). And shortcuts from file explorer don’t work – they revert to opening C11 projects in 15. (Of course “default location” in the hub can do it – but only for one file or folder)
Googly_Croft: Going to Open With.. doesn’t list C11 as an alternative; and pointing to C11 executable file in won’t the CPR in C11.
Raino, etc.: I don’t mind making C11 the default for opening a C15 project as will as C11 – I don’t have any C15 projects, as I’ve just installed C15 on my Windows PC. Is there a way to make C 11 the default?
Yes, but if you do I think in 6 months or a year you’ll realize it was a bad decision.
Right click on any .cpr file and in the Open with… menu select Choose another app
Then select Choose an app on your PC and locate the Cubase 11 .exe file and use Always
Can I ask why you are so resistant to using Cubase 15 after paying for it? Mostly it will behave just like Cubase 11 with a bunch of additional capabilities that you can use or ignore as you see fit.
And again. This is basic windows stuff.
Just tested it..works as always.
This is what I said, but the OP says it doesn’t work. Maybe it’s the way I explained it?
Thank you. I did try Right clicking one of my Cubase project files, and choosing “Open with…” but the only Cubase in the list is Cubase 15 - not 11. Several people have suggested going to the Cubase 11 executable folder – but clearly there’s nothing there that can direct Cubase to always open in C11.
Select always open with..find and select the Cubase 11 app.
Do you not find the Cubase 11.exe file in the folder?
Clearly it should be there. Do you have the Cubase 11 shortcut still on your desktop?
Right click on that and it will guide you to where the file is.
I have to ask..Is Cubase 11 still on / working on your set-up?