I can't find anything about this online, and I've uninstalled and reinstalled Arduino twice now and it hasn't solved my issue. This all just started today. I've transferred code before with no issues.
When I go to select my port, COM3 shows up several times. They are all selected and I cannot unselect them. Every time I plug my board into my computer, it adds another iteration. This is the correct port I have used before to transfer code.
The error message I receive says that I am not connected to my board at all. It is the same message I get when I try to send code without the board plugged in. I know it's plugged in, because it powers up an LCD screen that I have connected.
I've seen things about greyed-out ports, or not being able to find the right port, but nothing about this. It didn't help to uninstall and reinstall it. Please help.
The spurious upload error has been fixed in the hourly build of the Arduino IDE:
The problem of duplicate ports on the Tools > Port menu has solved separately in the beta build of the Arduino IDE (these are actually two different bugs that are triggered by the same circumstances), but that is only a cosmetic problem so you can use the hourly build and just ignore the duplicate ports.
EyeblightsEnding:
The error message I receive says that I am not connected to my board at all. It is the same message I get when I try to send code without the board plugged in.
I'm very skeptical that the exact error message is "you are not connected to your board at all". When asking for help here on the forum, it's much more helpful for you to post the exact and full error message rather than giving us an interpretation.