LOTR cards with speical characters and CVS file

I'm trying to upload a CSV file, but I'm running into a problem: the file won't upload because of the special characters like the ó in Arwen Undómiel. I got this message (Error: The server encountered a problem trying to import your file. Please check that it is a plaintext csv file and try again. Extra information: Invalid byte sequence in UTF-8 in line 71.)

So, are there any ideas on how to get around this?