I am running Ubuntu 14.04 (32bit) and want to upgrade to Ubuntu 16.04 (64bit). I have a separate home partition. Is it possible to share the home partition with both versions of Ubuntu whilst the transition goes through ?
You can not share a single
/home-partition with two different versions of Ubuntu.
Many files and folders are stored in the
home-directory. One part of this files and folders are your private data, such as in the folders
~/Downloads. Another part of files and folders are configuration-files (most of them are hidden by default and you will not see them in the file-manager unless you enable the option
show hidden files) and here the problem starts. Possibly some of the configuration-files are valid for both versions of Ubuntu, but not all of them.
You may easily share your private data by creating links to the old data-folders in the
/home-directory of the new version.
If you just want to install
14.04 (overwriting) then you can surely use the old /home-partition. You only need to set the mount-point for the partition and untick the formatting-checkbox during install, so your data are not deleted.
If you want to use both versions you could use a different user-name to install the new version of Ubuntu. If you use different user-names you could share the
/home-partition, as both versions would have it's own sub-directory in the
/home-folder, (/home/old_name and /home/new_name).
A problem is that it will be difficult to access the data-folders (like
Downloads, etc) in
/home/old_name when you use the new version of Ubuntu with a different user-name, you are not the owner of these files in this case.