Upload & Sell: On
How did you update? I'd expect the new catalog to point at the same file locations as the old catalog. Did you shift any images or their folders around without using Lr to do it ?
If you have not shifted the files at all then you can probably open a copy of your old catalog and the new Lr should convert it. Before doing that it might pay to reboot your computer and restart Lr, making sure that you're running the new one and not the old one.
If you have shifted your image files around or renamed folders then you made a mistake - shifting files should always be done within Lr to avoid the "missing files" problem. Perhaps you can tell what you did. If you simply renamed a single parent folder then it is very easily fixed. If you fiddled with lots of things then it may get messy.