James,Originally posted in cdnusers.org by adbeckett
Generally speaking this kind of error means that you have more than one well contact, with the metal connected to different nets. This means you've got a "soft connect" through the well (not quite a short, because the well is resistive). It may be that you're making a connection via the well, which is almost certainly not what you want!
So check what other well contacts you have in the same well, and what they're connected to. If the connections are made in metal as well as nwell, the error will (most likely) go away.