The spec of this inverter is 120VAC output, correct, as marked on the box? So the AC Volt meter on the inverter shows 222VAC?
It should not have any error at all if there is nothing connected to any of the AC outlet, it should come on and stay on and put out correct AC output.
Look at it this way, if you do not need to use the AC output terminal and just want to use the two AC outlet, the unit should not care if you have nothing connected to the AC output terminals, some of these units are not made to have Neutral and Ground tied together.
Do you have the link to the user manual or where you buy this unit from?I bought off of Amazon. There is no link for manual.