Frontsau

Seems like its a thread in a subforum for which you have no rights (you can't write or read in this subforum). In a forum like the KSP-forum, there are usally a few of those subforums. These are for admins, developers and other privileged to discuss things, which normal users should not be able to read. But what exactly the subforum is and why this thread is in there, I can't tell.

Either the way Camacha wrote (first code block in his reply) or with copy launch from 0. this will copy your program "launch" from the archive to your current volume. (On startup normaly the internal volume of your kOS module) IIRC you need some antennas to be able to access the archive after launch. Which antenna and how much of them depends on the distance to kerbin. With the file copied to your internal volume you will not run into the problem of not beeing able to access your program.

KSP is a singleplayer game in which you can basicaly do what you want. If you think, the revert flight button is cheating or undermines the challenge of the game: don't use it. This game is as hard or as easy as you want it to be. Nobody can prevent you from going into the config files for parts and build a super light, super strong and super efficient engine. For me, that wouldn't be too much fun, but maybe for someone else thats just what he/she wants. And its the same with the revert flight feature. If you don't like it, don't use it. If you think its okay: go ahead.

I had the same problem in V0.12.1. I switched to the pre release version posted here https://github.com/KSP-KOS/KOS/releases . That fixed the problem for me. I didn't run into any trouble with the pre-release yet. But didn't give it a great deal of testing either.