hwclock: ioctl(RTC_RD_TIME) to /dev/rtc to read the time failed: Invalid argument

This error occurred on Raspbian Jessie using an ARPI600. I was trying to set up the real-time clock. I could resolve the issue by running the following command: hwclock --systohc -D --noadjfile --utc after enabling it with the command echo pcf8563 0x51 > /sys/class/i2c-adapter/i2c-1/new_device 0x51 may differs on you installation. Run i2cdetect -y 1 to find the right value.