Kerbal Space Program

This was confirmed by sal_vager in a forum post

This is reproducible, happening every time for the given craft. I have a space station with a small docking port, and when I carefully put a new station mast onto the dock, it seems to couple correctly. However, when I then decouple the tug that brought the mast, it is taking the mast's deployable radiator, and in two of three cases the deployable solar panel as well. These parts then float in front of the tug as if attached where they were when the mast was being carried.

I am running stock v1.0.5.1028 on a Windows 10 64-bit machine, though task manager says KSP is 32-bit. I installed via Steam.

All of the crafts in question (the station, tug and mast) are from the most recent version.

To quote Sal:

??Okay, there's a really simple workaround for this, just quicksave then quickload, done, the craft will now undock with no issue.

Turns out your station was the necessary factor to reproduce this as I can only reproduce it when docking to your station and undocking without save/loading beforehand.

When your tug+tower docks to your station KSP must be messing up the paths to some of the parts, so when you undock you take the solar panel and radiator with you.

When you save KSP sorts itself out, so when you reload the parts are parented correctly and they stay where they should.

This happens in memory, by the time it's written to the persistent.sfs or the quicksave.sfs the problem is gone, so all the parts have the right parents in the docked save.

So there's no checking of the save to see what went wrong, as by that time it's already fixed, there's also no errors written to the log so there's no help there.

Also, if I dock your tug+tower to anything else the issue doesn't occur.

On checking over your ship in more detail I notice that your small docking port is the root of the vessel, that may be a factor, if you had used the probe as the root it may have been different.

I'll keep hold of the saves, and it may be an idea to post this to the KSP bug tracker, as the only way to debug this properly would be for a dev to watch what happens when your craft dock in the Unity editor.

It's an odd issue, and hopefully it'll be rare as it doesn't occur with other docking targets as my earlier pic showed, and thankfully it's easy to avoid.

So no need to scrap the ship just yet, you could try using the re-root tool in the editor (press 4, click vessel, click new vessel root) and see if future dockings with this tug on your station have the same issue, but as the docking port is the root I suspect you'll be rebuilding this for the next delivery anyway.??