Replace Zorin 12 w/Zorin 15 on dual boot with Ubuntu

Currently I have a dual-boot system with Ubuntu 19.04 and Zorin 12 installed. I would like to replace Zorin 12 with Zorin 15. (I don't care about saving anything from Zorin 12, but I would like to preserve the Ubuntu installation and still be able to dual-boot between Ubuntu and Zorin 15.) HOWEVER, when I boot Zorin 15 from a USB installation stick I'm told that "This computer currently has Zorin OS 12.4 (12) and Ubuntu 19.04 on it. What would you like to do?" At that point I'm given the options of:

1) Erase Ubuntu and reinstall (This option claims to wipe out all Ubuntu 19.04 programs, etc.)
2) Erase disk and install Zorin OS
3) Something else

What's MISSSING is an option to erase the current Zorin OS installation and replace it with the new Zorin 15 OS! I've looked at the "Something else" option, but not being that much of a Linux expert I couldn't see an obvious way of doing what I want. Any help/suggestions would be most welcome!

Hi, before you do anything to your system, backup any critical data from your Ubuntu install. Next run GParted to inspect your current installation - normally, Ubuntu and derivatives remove this after install so you could run Zorin 15 in live and just run GParted - just search for it in the Zorin menu search - make a note of the sda# of each partition - you will probably know which is which. Then delete the partition that is marked as Zorin (hopefully). Modern installs now seem to indicate what OS is present using GParted. Then you need to create 4 partitions to cater for Zorin, but before we get there, did you install Ubuntu using EFI (ESP)?

Thanks for the quick reply! To clarify the current disk partitioning I've attached a camera image from the "Something else" option. The Zorin and Ubuntu partitions are nicely identified, but I'm not sure exactly what to do with the OTHER partitions. (I gather that I'm supposed to delete the existing Zorin partition on /dev/sda1?)

This is an older system and does not use UEFI booting.

Hoping you can give me a little additional guidance....

OK, in GParted I would remove sda1 (delete it). Apply the change then in GParted, using 'something else' method, create a root partition for the system (30720 Mib = 30 Gb) - make it Primary and bootable firnatted to Ext4. Whatever space is left after this mark it as '/home' and format to Ext4 - then install the system to the partition marked as '/' at install time. The 'swap' partition should be left as is.

Will this approach maintain the dual-boot feature between Zorin (now version 15) and Ubuntu?
Thanks, Wayne

Yes it will. Make sure you install GRUB to sda (no number). Installing the something else way ensures that if your system goes west your data is retrievable which may not happen in your Ubuntu configuration.

While starting to follow your recommended steps I stumbled upon a far simpler method for accomplishing what I was attempting to do. Hopefully this approach, described below, may help some other users!

Here is what I ended up doing:

1) Use GParted to delete the /dev/sda1 partition containing Zorin OS 12.4.
2) Start the Zorin 15 installation from a flash drive
3) When asked what type of installation is desired, choose the (new) option to install Zorin side-by-side with Ubuntu & allow dual booting.
4) Allow the installation of Zorin 15 to proceed in the normal way.

Apparently, creating unallocated space by deleting the old Zorin partition triggered the installer to offer the side-by-side option.

Wayne

Whilst it might be simpler your data won't be so readily retrievable should the system baulk at any time - if a system file stops the system from booting due to a corrupt sector on hard drive you won't be able to access your /home - that is why I always recommend the 'something else' solution.

Probably true, but I'm never happy without a complete system backup that can be used (hopefully) to recover from any hardware or software error...