Migration Assistant - Error Transferring Files

I just bought a new MacBook Pro and was trying to use Migration Assistant to transfer my files. My old computer is a MacBook Air that I got in the summer of 2015. It still works pretty well, and it's completely up to date with macOS Catalina, version 10.15.2. But when I clicked on my old computer to try to transfer the files, it had a yellow exclamation point and said I had an error, something to do with the software being too old I think. But my computer is fully updated so I'm not sure what's wrong. What do I do?