Organizer will not run after upgrade from 16 to 24

Try contacting Elements support. You can start a chat session by clicking on the blue Contact Us button under the Help & Support menu at Adobe.com.

If you create a new catalog, does the Organizer open?  If not, uninstall and reinstall the program. 

OK.  (Sometimes users can't even get into the catalog manager.)

You should try converting the Elements 16 catalog again (and make sure you wait for the process to complete):

• Press the Shift key while launching the Organizer - the Catalog Manager will open
• Click on the Convert button - a new dialog will open
• Check the box to Show Previously Converted Catalogs
• If the Elements 16 catalog is located in the default location, it should show up in the list. 
• If you have moved the catalog to another location, you need to click on the Find More Catalogs button and navigate to the parent folder of the Elements 16 folder location.  Once selected, the catalog will show up in the  list.  If you can't find the catalog, search your computer for a file called catalog.pse16db.   It will be in your Elements 16 catalog folder.
• Once you find the catalog in the Convert Catalog list, select it
• Press the Convert button
• Wait until a message pops up confirming that the conversion has beens successful.
• Open the converted catalog.  It should have the same name as the original Elements 16 catalog.   During the conversion process a copy of the Elements 16 catalog will be created and renamed with a numeric suffix.

What didn't work?

Press the Shift key while launching the Organizer.  That should open the Catalog Manager.  Try to optimize and repair your catalog.  If that fails to work, you can try converting your Elements 16 catalog again.