Lightroom update to 9 ends up with Lightroom: Catalog-2.Ircat & Catalog.Ircat

[#1]

I am curious about this update and catlogs scheme.

The preferences is set to prompt me when starting (working through the Classroom in a Book), so all the catalogs show up.  If I select the older Catalog.Ircat I get a promt that asks me to select the new -2 version or to upgrade the old version. 

So, why didn't the upgrade just update the old catalog and then delete it because we have to use the new -2 version anyway. That being said, can we not just delete the old catalog?

[#2]

I am curious about this update and catlogs scheme.

The preferences is set to prompt me when starting (working through the Classroom in a Book), so all the catalogs show up.  If I select the older Catalog.Ircat I get a promt that asks me to select the new -2 version or to upgrade the old version. 

So, why didn't the upgrade just update the old catalog and then delete it because we have to use the new -2 version anyway. That being said, can we not just delete the old catalog?

[#3]

During the upgrade process a copy of your original catalog is created then upgraded to the new format (the catalog with -2 suffix). Doing this ensures that customers have a means of going back to their older catalog should they have issues with the lastest version of Lightroom. Obviously, the customer will also need to replace their copy of Lightroom with the previous version. 

[#4]

Many reasons why the upgrade does not automatically delete the older Catalog, but most importantly, that would go counter to the Lightroom "better safe than sorry" ethos. LR does nothing irreversible affecting files on disk, without the user's explicit confirmation.

Yes you can delete the old Catalog from the computer once you have confirmed that everything is working OK with the new converted Catalog-2. I suggest keeping aside a backup of the old one anyway, just in case. The new Catalog-2 can, if you wish, be then renamed - while Lightroom is not running - but if you are doing so, take care to also rename the associated .lrdata folders (holding your previews) identically. These do need to match up in their naming.

[#5]

Thanks to both of you who replied. I appreciate it 

DN