Whenever the simulator is launched and X-Plane notifies of an available update like in the picture below, select "Not Now".



The simulation will run normally, and Fly This Sim will notify when it is safe to update to the latest version of X-plane.


If "Update X-Plane!" is selected, and in the next window this is displayed:



Simply click "Ok", the Simulation will run normally, and Fly This Sim will notify when it is safe to update to the latest version of X-plane.

From this point forward, but sure to select "Not Now" on the initial window.