This error has been thrown for a while by the Generic Z-Wave Plus Thermostat driver, when used with this thermostat (GoControl GC-TBZ48). I keep forgetting to report it. For my ignorant eyes, it looks like the driver tries to set the time, but the thermostat doesn't have a clock?
That's not an error from this driver.. It's a scheduled event from a previous driver.. Copy this to a new driver code, switch to it, run the command, and then switch back and you should be good..
Not really, you can also change to "device" type and clear more than schedules. Sometimes is useful, but not required, and sometimes may have negative consequences, as Bryan pointed out.