I'm making a scripting tool, and embedding the script in the tool when I'm done.
If I try to edit the script after doing this, I run into this message

The file's encoding is invalid for Python 3.x. IDLE will convert it to UTF-8. What is the current encoding of the file?
I haven't had this pop up at all before, despite doing this same thing with other script tools, including previous versions of this same tool.
The script is just a normal .py file, created in Notepad++
What does this message mean? What do I enter to let me edit it?