During initialization of a multispecies case the following segmentation faul can occur under certain conditions: Node 3 Fatal signal raised sig = Segmentation fault 570f8120 CX_Primitive_Error 656d0cc0 seh_filter_exe 5719ec80 logical_right_shift 55d7ec30 _C_specific_handler 67ff1f80 _chkstk 67fa1020 RtlRaiseException 67ff0ba0 KiUserExceptionDispatcher 54de35b0 Switch_Species_Data This was observed for a case with a inlet species mass fraction being defined by an expression that depends on report definitions, i.e. (-1*{outlet_air}*{outlet-air-co2}*1[s kg^-1])/(0.0034) The expression result in this case actually is correctly non-dimensional and so the expression is correct. Workaround is to 1. set the expression to a constant value, i.e. 0 2. initialize 3. revert the expression to the original setting 4. start solver This issue does not occur in 2022 R1 and following.