The character is 0x82, which is not allowed in configuration files.
One of the fixes in 3.4beta02 was to print invalid characters properly. 3.3 was extending the sign bit, hence 0xFFFFFF82. (From the 3.4beta02 Release Notes: "Fixes a problem displaying the hex code for invalid characters in files.")
As the message says, that character is not allowed. The configuration file (and most other files) must be "plain text" files, which can only contain certain characters -- for example, no character with the sign bit (0x80) set is allowed.
You will have to contact whomever you received the configuration file you are having this problem with and have them resolve it.