Set charset in ErrorDocument messages
snippet in htaccess

Set charset in ErrorDocument messages

user1010

# set desired env variable to suppress iso-8859-1 charset
SetEnvIf Host ^ suppress-error-charset

# set desired 403 message with desired charset 
ErrorDocument 403 "<html><head><meta http-equiv='Content-Type' content='text/html; charset=utf-8'></head><body>Error 403 - Esta ubicación no es pública</body></html>"