Hello, I bet this question was already answered here but I cant find it using the search bar. How can I change the status of my propellant from "unstable" to something better? To minimize problems concerning the right propellant / engine combination, I have chosen to start with the prebuilt rocket "Kerbal X". But at start I have unstable propellant, even if I wait 1 minute to let it settle down. Other people on YouTube e.g. can start much earlier. If I start nevertheless it says "vapor in feedlines, shutdown". What can I do against it? I have tried it with the prebuilt Kerbal X rocket and I tried an own rocket approach (liquid H2 / O2 fuel and engine), both result in the same problem. Greetings Quaditz