I'm using just the basic TI-Connect CE software. I just edited a program on TI data editor (not Connect CE) and then tried to download this to my TI for the first time. This didn't work - I realized I had to use TI-Connect CE. I pasted my code in - it's 900 lines long - but in CE it was only about 100 lines, with multiple lines of code pasted together on one line (wasn't happy about this). After fixing it, when I try to save the program it gives me an error:
A token in .... is invalid, so we are not able to save it. Please edit, and try to save it again.
I used only the tokens I find on the TI. I have no idea what token is not working. What happened?

TI Connect CE may use different characters for certain tokens than TI Data Editor (for Mac I assume?). I would suggest saving the .8xp file from TI Data Editor and then opening it with TI Connect CE.

Yes, I'm on a Mac.

Now my computer says that my file can't be saved in data editor. This has never happened to me before. I don't recall doing anything new with my program tonight.

On a side note, the squared token seemed to be different (position of the 2 was slightly off). But even after changing all the old squared tokens to new ones, the program still doesn't save.

Make sure that you are using the tokens provided by TI Data Editor or TI Connect CE in their respective menus, and not copy-pasting from somewhere else. If this still doesn't work, I would recommend opening the original program with TI Connect CE and making your change with its editor. Alternately, you could upload the original .8xp file to Cemetech's SourceCoder3 IDE and then export a .8xp file to send to your calculator after editing.

I uploaded my project onto SourceCoder, then saved to my mac. I was at least able to save the file. But when I tried to send it to my TI, TI connect just said "One or more files are invalid and cannot be sent".