How Re-install 10.10.5 when recovery partition is broken?

Un Upgrade Install, such as to El Capitan, does the same thing. It does not, by design, erase of any of your files as it installs.

That approach was not suggested because it adds slightly more complexity -- not because it works differently.

You can use a third-party Utility such as DiskMakerX, to make a bootable USB-stick installer for 10.10 Yosemite, or for later versions as well.

You’d either have to try Internet Recovery—— or make a bootable USB thumb drive/stick , which isnt super hard. There are apps/software out there to help you do this. If you are very handy you can use the Terminal built into the MacOS to do that. The thumb drive/stick should be 8 gigs in size or larger. To start up from the usb stick after you have made it, restart, hold down the “option” key and plug the stick you made into your Mac. You should see Startup/boot manager with arrows underneath each potentially bootable drive. Pick the stick and click on it...

whew !!?

there is a way to remake the Recovery partion too... but i forget how right now, anyways you can find out how to do all that on your own....

jb

Hello, olaf261. yes, the Sierra installer is out there somewhere, but it’s not in the App Store unless you already “purchased” it. And you’re logged into the app store. Go to your name. Your account, then purchases and it still should be there under purchased items. Otherwise, try here:

https://www.macobserver.com/cool-stuff-found/macos-sierra-installer-download/

thats all i got. Why you’re still on sierra ain’t none of my business. I have a mac pro5,1 and have gotten up to 10.15.7 ( catalina) with no big problems at all. **Got a Radeon VII 16 gig gpu in there too... workin’ perfectly too. No tweakin’.... no overclockin’... oh well can live with that. ** with an unsupported unofficial patch which i can’t talk about here...

well, good luck to you

John B