Can't Undock Bug, How To Fix

[roscoe_jones]

So I don't know why it happens but I found out how to fix the undock bug from someone's suggestion in another thread (I forget where I saw it). Since Scott Manley recently encountered this bug in his most recent reusable space program, I thought I'd be a constructive member of the community and post my solution. Excuse me for my lack of proper annotations/formatting, this is probably the first time I've ever really posted in a forum. Maybe the mods can format it properly once I post it? Hope this helps out! It's also a selfish move because I want to see Scott Manley continue his trip to Moho!

The bug I'm talking about is when you right click on a docking port and click "Undock" but nothing happens. The reason this doesn't respond is because the docking port you right click knows its docked, but the docking port it's docked to does not. In the save file docking ports have a module that describes their docking behavior. The best way to find the particular docking port that you want is to disable crossfeed before going into the save file on the bugged port that says "Undock" but does nothing. Make sure crossfeed is enbled on every other port (in the whole save file is best, use find and replace to your advantage). Then ctrl+F "enablexfeed" and find the one that says "active = True" that's the bugged docking port. The parts of it you need are as follows, the bits that will have to be changed are bolded, the bits that you need to pay attention to are italicized:

Docking port that shows "Undock" button:

MODULE

{

name = ModuleDockingNode

isEnabled = True

state = Docked (docker)

dockUId = 4018712963

dockNodeIdx = 0

EVENTS

{

Undock

{

active = True

...... <---(indicates my own truncation)

DOCKEDVESSEL

{

vesselName = Thatsnomun RCS Spindle <----name of docked vessel (not a unique vessel in the save file, part of the mother vessel that is the conglomeration of docked vessels where you'll find these docking ports)

vesselType = 2

rootUId = 4159860481

}

......

Docking port that the bugged docking port is attached to (in its bugged state). Find this part by using the dockUId from the port above:

MODULE

{

name = ModuleDockingNode

isEnabled = True

state = Ready

dockUId = 0

dockNodeIdx = 0

EVENTS

{

Undock

{

active = False

......

Note in the above the second docking port doesn't have a "DOCKEDVESSEL" section within the module. You have to create it, which is the hard part. It should look like this:

MODULE

{

name = ModuleDockingNode

isEnabled = True

state = Docked (dockee)

dockUId = 3497032429

dockNodeIdx = 0

EVENTS

{

Undock

{

active = False

......

DOCKEDVESSEL

{

vesselName = Big Rig 1

vesselType = 5

rootUId = 975741807

}

This involves a little bit of remembering what the component vessel names are and finding the rootUId of those vessels.

Find the root ID of the vessel on which the docking port that has the bugged "Undock" botton is. Maybe someone can reply with a way to do this by analyzing the parent/root structure of the save file. I just happened to remember what the root part (the first part you put down in the VAB) of the connected vessel was, and it was the only one on my station. This could be difficult if the part you decoupled to put it on the station wasn't the root part you made in the VAB (i.e. you constructed a lifting vehicle, decoupled the payload, docked the payload to the station, and removed the lifting vehicle), because then the vessel has a name like "[Vessel Name] Debris" or "[Vessel Name] Probe" etc. I know you can find all this stuff with a lot of cross referencing and searching the save file. A LOT. Be prepared to take notes.

Once you found that rootUId, put that in the rootUId in the DOCKEDVESSEL section you're creating. Also carry over the vessel type (not sure how to find that one out) and the vessel name.

Once you have the DOCKEDVESSEL section assembled, paste it into the module for the docking port from which it is missing. It goes after the "ACTIONS" and end that module before the next part or other module (such as if you have the docking port camera mod installed).

Easy, right?

Step 2, you have to change the bit in the beginning of that docking port's module description. (see above).

Change "state = Ready" to "state = Docked (dockee)"

Insert the dockUId. That is the part UId for the docking port the has the active "Undock" button that doesn't do anything.

Once you have changed those values and inserted your new DOCKEDVESSEL section, you should be able to quickload the game and it should undock successfully!

Don't forget to make backups of all the different save games your changing and your persistent.sfs before making any changes! If you screw something up and the load goes bad, start over by copying and renaming your backups appropriately.

I really hope this is do-able for people who don't remember the component vessel names/root parts and for super complicated space stations that might have a bunch of duplicate component vessels that may or may not be bugged. Modders and people familiar with the save file structure, I hope you can help!

[roscoe_jones]

Here's my hypothesis for why this bug occurs.

Through researching this bug and in my own experience, it seems to happen on sub-vessels (a vessel docked to a conglomeration of vessels that doesn't show up as a unique vessel in the save file, but is named and indicated under the docking modules "DOCKEDVESSEL" vesselname = []...) that don't have any sort of control pod (manned or unmanned) as part of their vessel (there may be one on another sub-vessel somewhere in the rest of the mother-vessel, but not on the sub-vessel that doesn't get its docking port's state = Docked (dockee) set correctly). Someone can report if they've had this bug occur in another circumstance, but I've yet to see a report of one.

I think what happens is as the game is updating the persistent file, it updates the docking port on the vessel you're docking with the bugged one (changes it to state = Docked (docker) ) because, well, you're controlling it, so no problem. When the code that goes through and updates the rest of the craft after a successful docking gets to the dockee, though, I think it skips updating that docking port because it say "There's no control module, I can't update anything." So its state stays at "Ready" and doesn't get the DOCKEDVESSEL section.

This doesn't happen every time you dock in this fashion, and I've never dug into the code of the game, so I don't know why it does that, but it seems like a peculiar bug.

I hope this helps! :-)

[DMagic]

I'll have to try this out as this has happened to me many times. I currently have one vessel stuck to another as part of a three vessel craft. I'm assuming (as this has been the case every other time this has happened) that I will be able to undock two of the vessels, then undock the stuck port. But if that doesn't work this could be handy.

And it is definitely not limited to crafts with no control points. In every case I have had crafts with probes on both sections that could not be undocked. And they were all part of a larger complex of several docked crafts (at least 3 crafts docked together separately, each with their own probe core or command pod).

[DMagic]

Well this is a little weird. This worked in a few different situations, but there were subtle differences in how things were setup. A picture can probably best describe my situation, as it is very complex. Also, I take back what I said about this not necessarily being related to having parts with no probe core/command pod. Although the overall structure shown below has a manned cupola module, the component that I docked to (shown by the green arrow) doesn't have any control point. This was docked separately to the main base part, the one with the cupola. And I think this has been the case with all of the stuck docking nodes I have come across.

The red arrow points to the nun-functional dock, the one with the undock option; this is part of my construction rover, it does have a probe core. The yellow arrow points to the receiving port; it is on my kethane refinery, it also has a probe core. The green arrow points to the second port on the rover, it is used to attach to the base. This port works fine and can undock (though it does break off when I try this, I assume because of some stress caused by being stuck to the kethane vessel).

This is the docking code for the rover port (the one with the non-functioning undock option):

MODULE
				{
                        name = ModuleDockingNode
			isEnabled = True
			state = Docked (docker)
			dockUId = 1787168367
			dockNodeIdx = 0

			.... snip .....

                        DOCKEDVESSEL
					{
						vesselName = Moho Constructor
						vesselType = 3
						rootUId = 1324404093
					}

This is where my situation differs from yours. The DOCKEDVESSEL section (I think) should show the information for the other vessel. This shows the information for the vessel attached to the docking node that this section describes. Moho Constructor is the name of the rover, and the rootUId is the number from the rover's probe core.

The rootUId value, by the way, can be found fairly easily as long as you know the part name of probe core, or command pod you are looking for. For instance, the rover has an octagonal probe core, so I search up from the docking port for "probecoreocto" then check the UId number, which matches the one given in the description above. I'm not sure about the root id if you have separated the original root, but I think it just moves down to the next part. If you have a probe core on top of a decoupler, then the decoupler will become the root after you separate it, I think.

The other docking port, the one attached to the kethane refiner has this information:

    MODULE
				{
					name = ModuleDockingNode
					isEnabled = True
					state = Ready
					dockUId = 660524931
					dockNodeIdx = 0

The dockUId is correct (this is the 'uid' value for the rover's docking port), but there is no DOCKEDVESSEL section, the same as your situation. So I just copied the DOCKEDVESSEL section from the other port, with no changes.

When I reloaded, everything worked fine. The stuck red and yellow ports undocked, and the green port undocked, too, without breaking.

The next situation, though, turned out a little differently.

Here I have the rover, shown by the red arrow, stuck to the 6 way node above it. Like the last example, this base component has no control point, even though it is docked to 2 other vessels with control points. On top, where the green arrow points, is another set of stuck ports. This time, the stuck ports (the ones with the non-functioning undock button) belong to the base component, not the rover or the lander (the big orange thing on top).

Here is the code for the upper docking port, shown by the green arrow, which is attached to the lander called "Moho Skycrane":

MODULE
				{
					name = ModuleDockingNode
					isEnabled = True
					state = Docked (docker)
					dockUId = 2730892197
					dockNodeIdx = 0 

                                        ..... snip .....

                                    DOCKEDVESSEL
					{
						vesselName = Hermes
						vesselType = 2
						rootUId = 764744321
					}

Hermes is the name given to the base component (it comes from the tug that brought this part down from Kerbin), and the rootUId is for the docking port shown by the yellow arrow above. This port was directly attached to the original probe core, and it is the point used to connect this module to the main base. So far this is no different from the previous example.

The docking port on the bottom, however, makes no sense. This is the one shown by the red arrow. Here is its code:

MODULE
				{
					name = ModuleDockingNode
					isEnabled = True
					state = Docked (docker)
					dockUId = 660524931
					dockNodeIdx = 0

                                         ..... snip ..... 

DOCKEDVESSEL
					{
						vesselName = Moho Skycrane
						vesselType = 2
						rootUId = 1547116391
					}

This indicates that the bottom port is attached to the big orange skycrane on top. But that's obviously not the case. And the dockUId value, which represents the Id of the other docked port, is correct. The value shown above is the Id for the rover's docking port, not the lander's (and the same is true for the top port's code shown above, too, it matches the skycrane's Id number).

So I just switched everything around, I put the DOCKEDVESSEL info for the skycrane onto the top port of the base, and the info for the rover on the bottom port of the base. Then I put the info for the base component (the "vesselName = Hermes" info) into the rover and the skycrane port sections. And lo and behold, both components were then able to undock.

I realize this is long and probably utterly confusing to anyone who hasn't dug around in the docking port section of the persistence or quicksave file. But hopefully this can help someone. The sequence of events required for this to happen is way too complicated to reliably replicate, at least in my case, but it seems clear that something odd is going on with the docking system. The won't-dock bug seems similar to this, but simpler (I'll try to get around to posting a real bug report on that with a clean save, I think I know how to reliably replicate that problem), maybe it's not related though. I'll see if I can't find a way to dock together a few parts with no control points to replicate this in a simpler way than what I've shown here.

[SirJodelstein]

Thanks a lot for explaining the docking port module logic. In my case, the broken target port had just the wrong state (Ready instead of "dockee") and was missing the dockedvessel section. The "dockUID" was correct

[The Scientific Moustache]

yeah I had this problem and it was a part without a command module of any kind, it was a solar panel arm on a space station.

[Tarrow]

I've encountered it myself, and actually managed to get out of the situation with some weird tinkering about.

It occured with me when I put four station modules inline (three modules, one tugboat) each with a clamp-o-tron senior at each end.

Dock tugboat to one module (using front docking port) - no problem, all cot snr's still work.

Dock tugboat to second module (using rear docking port) - no problem, all cot snr's still work.

Dock either the first or second module to either of the docking ports on the third module - all cot snr's fail to undock, with the exception of the one attaching module 1/2 to module 3.

Undock the third module and all clamp-o-tron seniors on the module 1 / tug / module 2 assembly start working again as normal. I worked around the issue by dumping a module off the tug a few hundred meters away, docking the one the tug was still carrying then going to retrieve the last module. It was fine as long as the tug didn't have an object on each end at once.

I accidentally did something vile to the ship whilst attempting to edit the savegame (don't forget people - backups are good) but could probably try to recreate it if it's any help?

edit: well, inadvertently recreated it with the 2nd attempt at building the minmus station. Built three of the previous modules inline, brought up an x-adaptor to spread them out a bit and inadvertently ended up with a situation where the tugboat has welded itself to the x-adaptor. Surprisingly the same docking port playing up as last time. Other modules were able to undock from each other and manouver onto the other arms of the adaptor but tugboat will be functioning as a drive module until I pluck up the courage to delve into the save file. I've yet to send up the mining ship so looks like I'll hold off for a bit. Would be silly if it got welded to a docking port itself

Edited June 25, 2013 by Tarrow

[Tarrow]

Curiouser and curiouser - I was, through some trial and error, able to "unstick" the sticky docking port between the tug and the hub. At the time of my previous post edit it was welded to the lower arm of an x shaped hub, jamming after I docked the kethane processing rig to the opposing side of the hub. After shuffing the other modules I ended up with a habitat on each side arm though the tug was at this point still stuck. This evening I undocked the kethane processing rig from the hub to rotate it a bit to look tidier as part of the station, redocked it, and the stuck docking port between the hub and the tug suddenly unstuck.

Overall on both occasions undocking and redocking a different pair of docking nodes somewhere on the vessel has caused the stuck docking nodes to unstick. Fairly bizzare behaviour tbh - unless undocking that specific pair of nodes causes the game engine to rethink the ship structure (maybe another part becomes the root part?) and somehow catch the error in the bugged docking node set?

[YarTheBug]

Thanks for the write-up, Roscoe!

I just had this glitch on me and managed to fix it by fiddling around in-game. This certainly helped me understand what went wrong and how to fix it.

The glitch happened when: I docket a "new vessel" to a "station", then tried to detach that "part" of the station i just docked to.

In-game fix was:

1. Undock "new vessel" from "part", RCS retro lightly, and turn on ASAS.

2. Switch to "station" and undock "part".

3. Switch back to "new vessel" and RCS forward. Dock "new vessel" to "part"... (this step may require prayer and/or luck)

4. Dock same "part" port to same "station" port it just came from.

5. All is right with the world, and I can undock when needed.

Thanks again!

Yar

[DMagic]

There is almost always an in-game way to fix this, since it seems to only happen with multipart stations and bases, but I've run into one situation with no way to unstick the docking ports. I had two stuck ports on a 3-part vessel.

What I'm wondering, though, is whether anyone has found a repeatable way to get this to happen with a stock, or at least mostly stock, save game. I've tried many times to replicate this using a bunch of different rover types on the launch pad (I've had stuck ports on rovers before), but I can never get the docking ports to stick together.

And for anyone having issues with persistance file editing, make absolutely sure that you don't mess up any of the "{" or "}" entries; there are a ton of them, so it can be difficult to keep track. If you delete any of these it will totally screw up your vessel because it breaks how the game interprets the parts and how they connect to each other.

[Tobyz28]

There is almost always an in-game way to fix this, since it seems to only happen with multipart stations and bases, but I've run into one situation with no way to unstick the docking ports. I had two stuck ports on a 3-part vessel.

What I'm wondering, though, is whether anyone has found a repeatable way to get this to happen with a stock, or at least mostly stock, save game. I've tried many times to replicate this using a bunch of different rover types on the launch pad (I've had stuck ports on rovers before), but I can never get the docking ports to stick together.

And for anyone having issues with persistance file editing, make absolutely sure that you don't mess up any of the "{" or "}" entries; there are a ton of them, so it can be difficult to keep track. If you delete any of these it will totally screw up your vessel because it breaks how the game interprets the parts and how they connect to each other.

Ran into this a few times today. I think it may have something to do with sending up station modules with a decoupler attached to a docking node.

[ship Stage 1]

[ \ Node / ]

[Decoupler]

[ship Stage 2]

I do this when i don't want to carry a matching node ontop stage 2 and so i can properly drop stage 2 with the decoupler. If you hit space and execute the decoupler the node becomes bugged when you attach something to it (need to test further). If you right click on the node instead and "undock" it the decoupler just flies off the node as if it were docked and the node behaves as desired after.

I think Nodes were designed to be done this way:

[ship Stage 1]

[ \ Node / ]

[ / Node \]

[ship Stage 2]

And the way i initially set the ship up I think brought a bug to the surface.

[DMagic]

Do you mean the node won't dock, or it won't undock after using the decoupler? If it won't dock at all then the state is just bugged. You have to change 'State = acquiring' (or 'docked (docker/dockee)' sometimes) to 'State = ready' in the part description. This has happened to me before, or at least something similar to it.

It might also contribute to the 'won't undock' bug, too. I don't think I've tried this exact thing in one of my many attempts to find a simple way to replicate this bug. Actually, I think most of the times this bug has appeared for me have been doing what you described as your solution, undocking something (that isn't another docking port) from the port that eventually gets stuck.

[Sma]

I had this situation happen to me recently as well while trying to setup a kethane mining operation. I was building a fueling station in orbit around the Mun. It had 2 small drilling rigs attached. Sent one of the rigs down to drill and got it all filled up. Tried to send down the 2nd rig so I could launch the 1st to re-dock with the station but the 2nd rig wouldn't undock. I eventually got it to undock after messing around with the save file but thought I'd check previous saves. I thought maybe the problem had something to do with some new parts I sent up (an extended power module to dock with one of my drilling rigs as they originally dont have enough power to drill/convert without running low on power) but that wasn't the case. Turns out the docking problem occurred when I docked two fuel tanks together. I loaded the old save file (I back them up when I make major advances, like landing on the Mun (or learning how to do so through trial/error LOL) and checked and sure enough one of the miners wouldn't release/undock. I did undock one rig but the other wouldn't budge, that is until I undocked the two tanks at the center, that seemed to allow the bugged port to work like it should.

To explain a little more, I originally designed my launcher so the upper stage (munar inject stage) could become part of the fuel station. Had a skipper engine attached via Sr COT port(s). Drilling rig attached to rockomax adaptor via normal COT. So with the skipper engine undocked I could obviously use that end for docking to other tanks. For whatever reason, not totally on purpose, I ended up, from two separate launches having two of each drilling rig and fuel tank. So I figured I'd dock the two together(not thinking if the names were the same, don't remember if they were or not). Everything seemed fine, I was able to undock one of the miners take it down fill up and get back to the station. Didn't know there was a problem until today. My guess is that it may have something to do, at least in part, with ships having similar names. Oh also all four pieces have the stock remote control unit (so I don't think that has anything to do with it, at least in my case anyway), and other than kethane tanks/convertor and drills, no other mods were used on this particular mission.

I might have also had a docking port connected to a coupler, though I can't be 100% sure on that one though. I guess next time I'll make sure to change names of things before docking them, just incase thats it.

Edited July 8, 2013 by Sma

[codepoet]

Arrrgh! I have to say "me too" I have had this happen,and it is very annoying. Thanks to this thread I was able to rescue my craft(s). I learned a few things in the process:

...

Find the root ID of the vessel on which the docking port that has the bugged "Undock" botton is. Maybe someone can reply with a way to do this by analyzing the parent/root structure of the save file.

I realised that the parts are implicitly numbered starting from 0 by the order that they appear in the vessel, and this can be used to build up the tree using the parent value, so I took a copy of the vessel and went through adding in an ID for each part, and was then able to visualise the craft in my mind as I read through it because the parent ID tells you what each part is attached too. Hard work, but at least it makes it possible to navigate the parts, and make notes on paper as to what the important parts of the vessel are:

I just happened to remember what the root part (the first part you put down in the VAB) of the connected vessel was, and it was the only one on my station. This could be difficult if the part you decoupled to put it on the station wasn't the root part you made in the VAB (i.e. you constructed a lifting vehicle, decoupled the payload, docked the payload to the station, and removed the lifting vehicle), because then the vessel has a name like "[Vessel Name] Debris" or "[Vessel Name] Probe" etc. I know you can find all this stuff with a lot of cross referencing and searching the save file. A LOT. Be prepared to take notes.

I discovered that it was possible to set various differnt parts as the rootUID, and the code would rehang the tree (of interest to me as I as asking how to achieve this in the VAB a few days ago) using the part you specified as the new root. I think that from this point of view it is probably best to choose the probe-core / command module that you WANT to be the root of that part of the vessel when you undock.

I also suspect that this is significant in what causes the problem, ie it occurs in certain situations when one of the craft being docked does not have the probecore / command module as the root of the tree. This can occur if you add an extra probe core to your craft and then blow some decouplers or similar to seperate it form the probecore that was at the root of the original craft. (In my situation I hadd attached probe cores to empty jumbo tanks that I intended to use to dock with and use to ferry fuel from a refinary. Once in orbit I blew the decouplers to seperate them from the craft that lifted them to orbit, but it all went wrong when my tug tried to pick them up. I tried to reduce this to a simple test case, but without succcess

Once you found that rootUId, put that in the rootUId in the DOCKEDVESSEL section you're creating. Also carry over the vessel type (not sure how to find that one out) and the vessel name.

I think the vessel type just sets whether it is a probe or rover or base etc, and is easily changed in game once undocked.

Step 2, you have to change the bit in the beginning of that docking port's module description. (see above).

Change "state = Ready" to "state = Docked (dockee)"

Insert the dockUId. That is the part UId for the docking port the has the active "Undock" button that doesn't do anything.

Once you have changed those values and inserted your new DOCKEDVESSEL section, you should be able to quickload the game and it should undock successfully!

I wasted a lot of time because I had not realised that when you do undock, the parts are not immediately set to the ready state, but too the "disengaged" state. Only once you have reached a seperation distace of 2meters (or whatever value is specified in "unfocusedRange") is the state set to ready and you are able to redock. I assuem this is to stop undocked ports immediatly redocking, but it made me think that it was still messed up as I could not redock!

I really hope this is do-able for people who don't remember the component vessel names/root parts and for super complicated space stations that might have a bunch of duplicate component vessels that may or may not be bugged. Modders and people familiar with the save file structure, I hope you can help!

Thanks so much for posting this, it was really helpful. as I said above I suspect that if you go through the whole craft and make note of all the docking port and probecore IDs and how they are connected you can fix it up without needing to remember how the craft to constructed.

[brainsalad]

...

Your post helped me resolve a stuck docking occurrence; thanks!

My stuck docking situation:

I have a base on Duna with docking ports on the side. These ports are provided for big rover trucks to back up against, not unlike a loading bay behind a store or factory. So, they're pretty high off the ground.

I constructed a truck back on Kerbin. Not knowing the exact height of the Duna base docking ports, I equipped the truck with magic rams capable of raising it up a few meters. After dispatching this truck to Duna and backing it up against the base, the truck's massive scale became apparent. It's of ludicrous proportion; its docking port stands high above those of the diminutive base.

So, I built an adapter with docking ports on both sides and sent it to Duna on a sky crane. I attached the adapter to the truck, detached the other end from the crane, and backed the truck up against the station such that the docking port previously attached to the crane now attached to the station. Kerbals flowed through the adapter tube like hyperactive gerbils, filling the truck and eager to finally tear across Duna in god's own $70 million stretch SUV.

A crushing disappointment: the adapter docking port attached to the truck refused to release. Jeb pointed out that it does work to undock the station end and then the truck end, causing the adapter to fall into the red sand where it would forever remain. Alternatively, the adapter could remain attached like some deranged scorpion tale as the SUV careened about the austere Dunese landscape.

DMagic's post showed me where to look. The srf file indicated that the adapter port docked against the truck listed its mate as being the sky crane, and the port on the truck attached to the adapter as undocked. Both had correct dockUIds, so it was a simple matter to fix the other fields and add DOCKEDVESSEL section to the truck's port. I loaded the modified srf and finally undocked the adapter from the truck.

In the future, I'm going to put a remote command module on all such adapter parts so that they aren't inert. Hopefully it's just inert segments that cause stuck docking.

[Apollo13]

This bug needs to be fixed, rather than requiring players to machinate through a convoluted exercise.

It would truly warm the cockles of my heart (what are cockles, anyway?) if a near-term weekly status report stated the following from one of the devs:

In addition to creating shiny new toys and features, I spent half-an-hour to determine the cause of the undock bug and fixed it. You should see in vers. 0.22.

But then again, there's a better probability of me having a beer with Santa Claus, the Easter Bunny, and the Tooth Fairy today...

[KerbMav]

They always overlook Sandman just because he cannot talk ... poor fellow ...

And funny how it is always just half an hour ...

[Mishkin_007]

So I don't know why it happens but I found out how to fix the undock bug from someone's suggestion in another thread (I forget where I saw it). Since Scott Manley recently encountered this bug in his most recent reusable space program, I thought I'd be a constructive member of the community and post my solution. Excuse me for my lack of proper annotations/formatting, this is probably the first time I've ever really posted in a forum. Maybe the mods can format it properly once I post it? Hope this helps out! It's also a selfish move because I want to see Scott Manley continue his trip to Moho!

The bug I'm talking about is when you right click on a docking port and click "Undock" but nothing happens. The reason this doesn't respond is because the docking port you right click knows its docked, but the docking port it's docked to does not. In the save file docking ports have a module that describes their docking behavior. The best way to find the particular docking port that you want is to disable crossfeed before going into the save file on the bugged port that says "Undock" but does nothing. Make sure crossfeed is enbled on every other port (in the whole save file is best, use find and replace to your advantage). Then ctrl+F "enablexfeed" and find the one that says "active = True" that's the bugged docking port. The parts of it you need are as follows, the bits that will have to be changed are bolded, the bits that you need to pay attention to are italicized:

Docking port that shows "Undock" button:

MODULE

{

name = ModuleDockingNode

isEnabled = True

state = Docked (docker)

dockUId = 4018712963

dockNodeIdx = 0

EVENTS

{

Undock

{

active = True

...... <---(indicates my own truncation)

DOCKEDVESSEL

{

vesselName = Thatsnomun RCS Spindle <----name of docked vessel (not a unique vessel in the save file, part of the mother vessel that is the conglomeration of docked vessels where you'll find these docking ports)

vesselType = 2

rootUId = 4159860481

}

......

Docking port that the bugged docking port is attached to (in its bugged state). Find this part by using the dockUId from the port above:

MODULE

{

name = ModuleDockingNode

isEnabled = True

state = Ready

dockUId = 0

dockNodeIdx = 0

EVENTS

{

Undock

{

active = False

......

Note in the above the second docking port doesn't have a "DOCKEDVESSEL" section within the module. You have to create it, which is the hard part. It should look like this:

MODULE

{

name = ModuleDockingNode

isEnabled = True

state = Docked (dockee)

dockUId = 3497032429

dockNodeIdx = 0

EVENTS

{

Undock

{

active = False

......

DOCKEDVESSEL

{

vesselName = Big Rig 1

vesselType = 5

rootUId = 975741807

}

This involves a little bit of remembering what the component vessel names are and finding the rootUId of those vessels.

Find the root ID of the vessel on which the docking port that has the bugged "Undock" botton is. Maybe someone can reply with a way to do this by analyzing the parent/root structure of the save file. I just happened to remember what the root part (the first part you put down in the VAB) of the connected vessel was, and it was the only one on my station. This could be difficult if the part you decoupled to put it on the station wasn't the root part you made in the VAB (i.e. you constructed a lifting vehicle, decoupled the payload, docked the payload to the station, and removed the lifting vehicle), because then the vessel has a name like "[Vessel Name] Debris" or "[Vessel Name] Probe" etc. I know you can find all this stuff with a lot of cross referencing and searching the save file. A LOT. Be prepared to take notes.

Once you found that rootUId, put that in the rootUId in the DOCKEDVESSEL section you're creating. Also carry over the vessel type (not sure how to find that one out) and the vessel name.

Once you have the DOCKEDVESSEL section assembled, paste it into the module for the docking port from which it is missing. It goes after the "ACTIONS" and end that module before the next part or other module (such as if you have the docking port camera mod installed).

Easy, right?

Step 2, you have to change the bit in the beginning of that docking port's module description. (see above).

Change "state = Ready" to "state = Docked (dockee)"

Insert the dockUId. That is the part UId for the docking port the has the active "Undock" button that doesn't do anything.

Once you have changed those values and inserted your new DOCKEDVESSEL section, you should be able to quickload the game and it should undock successfully!

Don't forget to make backups of all the different save games your changing and your persistent.sfs before making any changes! If you screw something up and the load goes bad, start over by copying and renaming your backups appropriately.

I really hope this is do-able for people who don't remember the component vessel names/root parts and for super complicated space stations that might have a bunch of duplicate component vessels that may or may not be bugged. Modders and people familiar with the save file structure, I hope you can help!

I appreciate you trying to come up with a fix but this made very little sense to me. Squad needs to fix this bug.

[Snarfster]

I had this issue with my tug delivering two kethane tanks to my minmus orbital refinery. (One tank on the bottom, one on the top).

I eventually solved it by undocking the tug (with tanks attached) then, at a distance, undocked the tank (now it worked) and redocked the tank. Then redock to the refinery.

For some reason that was enough to fix it. (And it sure went quicker than searching through that persistent file.)

[Stankleberry]

Either blast the rocket on the docked ship wildly until the docking ports break off or perhaps smash another rocket into the docking port area until it's apart.

[whistlehead]

Thanks OP, saved my Mün mission!

[Damaske]

I ran into this once before and simply rolled the SSTO till the dock broke off landed it and then destroyed the station and put up a new one.

The one thing i can think of is that the ships were both unnamed and thus has no unique name and shared names docking = confusing and bugging out. THUS i feel that EACH ship even if unnamed/unsaved SHOULD be tracked and given a unique name something like unnamed000001, and so forth till unnamed999999 then it rolls over to unnamed000001. In theory if someone makes and flies 1 million unnamed ships really fast they are troubles.

SQUAD: PLEASE FIX THIS STUPID DOCKING BUG!

[Waster]

So the big day is finally here for .23. Was surprisingly able to open my .22 career save and the first thing I tried was to undock all of my stuck ships.

NO JOY!

I have to assume that the fixed docking ports bug described in KerbalKon is only for newly begun careers.

[Semtex89]

... And for anyone having issues with persistance file editing, make absolutely sure that you don't mess up any of the "{" or "}" entries; there are a ton of them, so it can be difficult to keep track. If you delete any of these it will totally screw up your vessel because it breaks how the game interprets the parts and how they connect to each other.

Wish I'd read that 10 seconds ago - now my refueling station consists of a Stayputnik and one thoroughly misplaced RCS block....

[DeepSpaceDutch]

Well damn, I am having a similar problem as the ones described in this thread. Unfortunately it is a bit different and that's why I am not having any luck fixing it. Hopefully somebody here can help me because it's seriously spoiling the fun in setting up my first Kethane infrastructure.

So here's the dealio;

I'm constructing a large Kethane storage station in orbit around the Mun. I thought it would be cool to have a docking module with 4 translating arms (using Infernal Robotics) with docking ports at the ends. However, the instability this module created when a ship docked was a lot less fun, so I decided to use a derelict Kethane Shuttle to disconnect this docking module and replace it with a more conservative non-moving-parts docking module. Here's where the "fun" started, I docked the Kethane Shuttle (below the green arrow in the screenshot) to the docking port on the bottom of the docking module. Then I proceeded to click the Undock toggle on the docking port next to the red arrow. The plan was to back away and have the docking module and shuttle crash on the Mun. As you might have expected nothing happenend, -insert explicit here-.

Luckily I found this thread and started poking around in the persistence file. To my horror I found that my problem is not exactly the same. I did find the buggy docking ports using the trick in the OP (set Fuel transfer on offending docking port to OFF and look for enablexfeed = True)

Here's why;

the code snippet below is the same for the docking ports near the red and green arrow (Undocking the docking module/kethane shuttle is impossible, only undocking the kethane shuttle is also impossible).

There is no DOCKEDVESSEL section for either ports and the state is set to Docked (same vessel). Also I could not find any reference to the original module names (KethStation 1 - Docking Module Mk1 & KethShuttle - Mun 1) of the docking module nor the kethane shuttle in the persistence file.

I'm fearing the problem is that the game now sees my station as one complete craft instead of docked modules.

Anyone got any ideas?

				MODULE
				{
					name = ModuleDockingNode
					isEnabled = True
					state = Docked (same vessel)
					dockUId = 1753449553
					dockNodeIdx = 0
					EVENTS
					{
						Undock
						{
							active = False
							guiActive = True
							guiIcon = Undock
							guiName = Undock
							category = Undock
							guiActiveUnfocused = True
							unfocusedRange = 2
							externalToEVAOnly = True
						}
						UndockSameVessel
						{
							active = True
							guiActive = True
							guiIcon = Undock
							guiName = Undock
							category = Undock
							guiActiveUnfocused = True
							unfocusedRange = 2
							externalToEVAOnly = True
						}
						Decouple
						{
							active = False
							guiActive = True
							guiIcon = Decouple Node
							guiName = Decouple Node
							category = Decouple Node
							guiActiveUnfocused = True
							unfocusedRange = 2
							externalToEVAOnly = True
						}


						<< .... >>

						EnableXFeed
						{
							active = True
							guiActive = True
							guiIcon = Enable Crossfeed
							guiName = Enable Crossfeed
							category = Enable Crossfeed
							guiActiveUnfocused = False
							unfocusedRange = 2
							externalToEVAOnly = True
						}


						<< .... >>

					}
					ACTIONS
					{
						UndockAction
						{
							actionGroup = None
						}
						DecoupleAction
						{
							actionGroup = None
						}
					}
				}

Screenie: