This message appears because you have not specified a user option byte for a device of the RL78 family.
Make sure to specify a user option byte by using the -USER_OPT_BYTE option of the linker or in an assembly-language source file.
If you use a specification in an assembly source file, you need to define the on-chip debug option byte as well as a user option byte.
(Example) Specification in an assembly source file
.section .option_byte, opt_byte
.db 0xFD ; address 0xC0
.db 0xFE ; address 0xC1
.db 0xFF ; address 0xC2
.db 0x04 ; address 0xC3
|CS+ (formerly CubeSuite+)|
|C Compiler Package for RL78 Family|