How to prevent the docking port bug

[jarmund]

Now and then I find myself editing save files to fix the dreaded docking port bug, as per [URL="http://forum.kerbalspaceprogram.com/threads/78863-FIX-Dock-Undocking-Bug-in-0-23-5"]this[/URL] guide. As this is a pretty tedious ordeal (especially after it happening on my previous Jool-5 expedition on every single lander, both for undocking and redocking), is there any data as to how this happens in the first place? What are the DOs and DON'Ts if I want to avoid this bug?

[JTpopcorn]

I thought that got fixed, that forum page you reference is from 0.23.5...

[Waxing_Kibbous]

One of the few times I have used docking ports I somehow stuck it facing the wrong way- they don't seem to snap to parts in the VAB/SPH as others do, allowing them to be put on wrong. Maybe this is what is happening? What happened on my end was that I stuck 2 things with ports together in the VAB and couldn't separate them on Minmus because one was on wrong. Using a bit of violence I could eventually unattach them however haha.

[Aegeas]

[quote name='Waxing_Kibbous']One of the few times I have used docking ports I somehow stuck it facing the wrong way- they don't seem to snap to parts in the VAB/SPH as others do, allowing them to be put on wrong. Maybe this is what is happening? What happened on my end was that I stuck 2 things with ports together in the VAB and couldn't separate them on Minmus because one was on wrong. Using a bit of violence I could eventually unattach them however haha.[/QUOTE]

Don't know if this is the same thing but occasionally in a stack the top item gets attached to the bottom item and skips the middle item if the attachment node (big green sphere in the VAB) of the top item is bigger than the one of the middle item.

For example occasionally I find that and engine gets attached to a fuel tank below rather than the top of the decoupler so when it tries to decouple the bottom stack gets stuck because the engine and tank below are still attached.

If this is a similar problem the work around I have found for this is to use the 'root node' tool if that is even its name to go through the stack and one part at a time make it the root which tends to re-order the connections making sure you don't get the bug where a part 'skips' the part below and attaches to the part below that if that makes sense.

Well this is just a VAB method to ensure all parts in a stack are parented correctly so wont help anything after launch.

Just throwing it up as a method in case it relates to the docking problem.

I'm thinking this could occur if the docking face of a docking port is attached to a stack part other than another docking port face.

[Waxing_Kibbous]

When it comes to attaching things to decouplers I find the KER readout is super useful.

As a side note. I notice that when building in the SPH parts won't orient automatically, eg you have to manually rotate a nosecone to put it on the back of a jet- combine this with the docking port's ability to attach very loosely and you get a recipe for disaster.

[Snark]

[quote name='Waxing_Kibbous']combine this with the docking port's ability to attach very loosely and you get a recipe for disaster.[/QUOTE]

Yah, I long ago got in the habit of always force-snapping docking ports when placing them (i.e. holding down the alt key so they're forced to be placed only on the node). It's just too inconvenient to manually try to mouse them into the right place.

[Claw]

The bug referred to in the OP isn't due to mis-snapping, or inadvertently surface attaching docking ports together.

I wish I knew what caused it, because then it would be easier to fix. As it stands, it's one of those bugs that's known to happen, but no idea why or how. So, unfortunately, I don't know what to tell you to avoid it.

No, it's not been fixed. And yeah, it's been around a while.

Cheers,
~Claw

[lextacy]

As CLAW states, its a nasty lil bug that makes its way to every version. BUT !!! There are ways to treat the problem , since there is no vaccine.

1. You can use hyperedit and place your craft more than 2.5km away from where you are docked. Its important to make sure your orbit is moved by that much or you’ll be in physics range and bad stuff will happen.

2. You can make all your docking ports a decoupler with a 0 force. This requires you to place a code into a .cfg file . I can help you with this one if you want cuz im fairly versed in module coding. The possible side effect on this method is that you will lose your port once its jettisoned. Try to decouple from the ship side, not the station side. Most the time the undocking ship is leaving a space station to be disposed of anyway....aka Soyuz, Dragon ect.

[problemecium]

I haven't had it in 1.0.5, so I've been crossing my fingers, but it wasn't on the list of bugs fixed so I'm trying not to get too hopeful. I doubt it'll ever get fixed, really. SQUAD seems to have every other priority over fixing problems that generally only affect giant space stations.

In the meantime, I recommend quicksaving before every major docking operation. Sometimes if you restart KSP, load the quicksave, and then try again, the bug spares you.

[Claw]

[quote name='parameciumkid']SQUAD seems to have every other priority over fixing problems that generally only affect giant space stations.[/QUOTE]

That might be a bit dramatic. As I noted above, the replication is unknown. It's hard to track down a bug when the cause is completely unknown, and it happens relatively infrequently. So it becomes a question of how much time to spend tracing a single bug vs. fixing others, or working on content.

A bug always feels like the worst bug when it afflicts someone. If it happens frequently to you, then please try to keep note of what's happening. Perhaps you can help find the cause. It took me almost a month of working with a couple other people and poking about to track down a claw bug. And even then, it didn't replicate 100% of the time. That was only one bug, and it took a lot of time.

The docking bug is another one of those bugs that is really annoying and known to happen, but the steps are completely elusive. Same with the "crashed into VAB" bug. Bugs that take hours to trigger with unknown steps are just about impossible to squash.

Cheers,
-Claw

[Kerbart]

Few things I've noticed, and if any of this is already known to the OP feel free to flame. I can handle it. :)

I think there are two "can't undock" problems.

The first is what seems the primary problem in this post. Somehow the ports are still connected but have a status "undocked." And since you can't undock what isn't docked... You get stuck. I might be wrong but I got the impression that this is a problem that primarily happens with the large docking port. I haven't encountered any undocking problems of this kind anymore since I've stepped away from using the large docking port for "docking" (as in: with the intention of undocking later) purposes. I still use them to piece large stations together (they're a lot stiffer than the medium and small ports after all) but I hardly ever disconnect them once they are together. I've never encountered the bug anymore since I stopped undocking large ports.


The second seems to happen frequently with medium ports when the docking collars slide behind each other. The ports are truly undocked but somehow still interconnected and can't get lose. Spinning might work to decouple but more often than not it rips one of the ports off completely which is often not desirable. A much simpler solution, since as far as KSP is concerned, the two parts are not connect, is time warp -- without physics active the two parts will simply float apart and the problem fixes itself.