How are they fixed?
The simplest fix: First check whether the ground wire was left unconnected by mistake and then you just need to connect it in the receptacle. This will not be the case if the receptacle was originally installed as an ungrounded (2-hole) receptacle back in the day before it was common to ground receptacle and there is no ground wire present. Cost: A couple of minutes of an electrician’s time. If you don’t need a ground at this receptacle because you will only be plugging in lamps or other two-prong cords, then you can change the three-hole receptacle to a two-hole receptacle. Most things, such as lights don’t need a grounded-receptacle. Cost: A couple bucks for the receptacle and a few minutes of an electrician’s time. If you want to plug in three-prong cords (that is, appliances that require a ground at the receptacle to be safe),but you are not concerned about protecting the equipment from damage, just with protecting people from possible shock, then you could install a ground fault c
