What should I do when I cannot program EEPROM using the FT_Prog utility?

Please ensure that our SPI EEPROM chip is 93C46B/56B/66B, and that the EEPROM is configured in 16-bit data mode. Pull the ORG pin to VCC to put the EEPROM into 16-bit data mode. Please not however that 94C46 is not supported. This applies to FT232H, FT2232H, FT4232H and FT23xHP, FT223xHP, FT423xHP which all use an external EEPROM for configuration.