@User: First, the error message refers to parasitic capacitances, and so whatever is wrong is, I think, minor. These errors seem to pop up for a number of different reasons and every now and then I go track one of them down and eliminate it, but the errors persist for other reasons. In this case the node in question is the drawn pwell; there might be an issue with the way magic extracts the pwell or substrate, especially if you have a deep nwell under it.