Since version 1.9.2 (Catalyst) I am getting error messages about footnotes for every note I open, whether it has footnotes or not. Even new notes without text get this message.
Can you open the developer console and grab the exact message?
Mac: Cmd + Option + I
Windows/Linux: Ctrl + Shift + I
Then click the Console tab and trigger the error by opening a note
Look for any red error messages, especially ones that mention a file path or plugin. That’ll tell us exactly where it’s coming from. Without that, we’re just shooting in the dark.
This most likely will be moved to help, this doesn’t seem to be a core issue, but a plugin error.