I have attached a photo of the error which is shown while trying to do nonlinear analysis in sap2000. I don not why it is showing this error. I have assigned the hinge property properly.
sometimes these problems occurs in SAP2000 and ETABS which should redefined some properties. Are you regenerated hinge properties and this error appeared again?
You can reduce the Monitored Displacement, as shown in the pic, or just unlock and re-run and try again. I had a similar problem, I found a Youtube video which was very helpful
First run all load cases except pushover load case and then run push over load case .It will solve the problem. As hinges takes shear and moment values from other gravity load cases.