Object reference not set to an instance of an object?

I was running a digester simulation and I encountered with this error 'Object reference not set to an instance of an object?'

DWSIM 05-09-20, 3:11 p.m. FATC25
The issue in this simulation is due to the user-defined compounds added. The added user-defined compounds have some missing physical properties because of which the volumetric flow rate of the initial feed stream is not getting calculated and causing errors in the subsequent material streams.
25-09-20, 11:11 a.m. Priyam_Nayak

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