Umfpack_di_numeric failed error

I am trying to solve natural convection flow inside a square cavity for a higher value of Rayleigh number (Ra=10^8), for this I took mesh = 200 but received “umfpack_di_numeric failed” error. How to deal with this problem?

I thick you matrix is not invertible or to big

Thank you Professor @frederichecht , how I can overcome this problem?

Debug, I try to under where is the problem.