Fluid is no longer in the vapor phase because the fluid temperature/pressure is...

A Warning message in AFT Arrow

Full message is:

Fluid is no longer in the vapor phase because the fluid pressure is above the Saturation Pressure for the following...

The solution indicates that the temperature and pressure conditions at the specified pipe are such that one or more gas components has reached saturation conditions. Arrow's solution accuracy will be decreased, as Arrow's calculations always assume that the fluid is a superheated gas.