Upon opening MySQL Workbench to edit the MySQL option file and you might receive the following error:

 'Unhandled exception 'charmap' codec can't decode byte 0x8d in position 7799: character maps to <undefined>'

 To resolve this error:

Close Workbench and open the my.ini file located at C:\ProgramData\MySQL\MySQL Server 5.7 (in our currently supported version), in Notepad++.  From the "Search" menu select "Find Characters in Range":

Ensure "Non-ASCII Characters (128-255) is selected and click "Find"

It will usually locate a string of text containing smart quotes i.e., “” which you must replace with normal double quotes "".

 # range from 1 to 2^32 − 1. “Unique” means that each ID must be different

Save the file and re-start MySQL workbench and you should be able to edit the options with no further errors.