Bob: When I upgrade to Lightroom Classic 11.0 will all the photos in my Catalog be accessible as well as my user presets?
Andrew: Yes they will. When you open the latest version of Lightroom Classic (11.0) it automatically asks to upgrade your Catalog to work with the latest version. Once that’s done you’ll have access to all the photos in your Catalog plus all your presets. Nothing is lost during the upgrade.
This is normal behavior. Whenever Lightroom Classic does a major version upgrade (i.e. from version 10 to version 11, as in the recent October 2021 update) it asks for permission to upgrade your Catalog.
It happens because Lightroom Classic needs to update the Catalog and previews files to work with the features in the latest version of Lightroom Classic.
For peace of mind, Lightroom Classic creates a new Catalog file, leaving the earlier one in place in case you decide to roll back to the previous version of Lightroom Classic.
It also lets you rename the Catalog file to make it easy to see which Catalog file is your current one. The default is to append it with v11 (see the above screenshot).
After the upgrade I suggest you move the older Catalog to a new location so you don’t open it accidentally. If you do, you’ll see the message to upgrade the Catalog again. That’s not a bad thing as it’s a warning signal that indicates you may have tried to open the wrong Catalog.
Most photographers work with a single Catalog. If this applies to you go to Preferences > General and set When starting up use this catalog: to Load most recent catalog. Now every time you start Lightroom Classic it will automatically open the correct Catalog.