Portals in the Nether are linking to a new portal

This is because portals are not actually linked. When you enter a portal, the game calculates where you should come out and checks for a nearby portal. If it does not find one, it will create a new one. This may not always be in the right location. If it can't create a portal, due to obstructions, it will create one somewhere else.
To fix this, find out your Overworld portal's coordinates (by pressing F3), divide X and Z by 8, go to the Nether and go to the coordinates you calculated. Build a portal there and destroy the old one. Your Nether portal should now always bring you back to your original Overworld portal.

Thanks, but I don't have to fix it. Instead the calculated position should always be the right location.

@Daniel Lunsford: You should also vote on this bug if you're experiencing it as well.

I experienced this error, for the first time, in 1.4.2 (after having briefly used the 1.4.3 pre-release on the same world, and restored 1.4.2). I later destroyed the "wrong" destination portal, went back to the start portal, returned from the Nether, and the destination was "corrected" to the proper start portal.

Possibly unrelated: each time I return from the Nether through either the start or "wrong" portal, my compass points to the wrong "north" until I exit and reload the game (after which, it's still "off" by a few meters).

Yes this has happened to me, and not only that, but the direction compasses point to when going through a nether portal and back, is different. It doesn't point to the spawn, and I almost lost my house because of that.

@Alec Gorsse: Than you should probably also vote for this bug-report.

I'm not 100% sure I experienced this exact issue but I can vouch that nether portal behavior is not as expected in 1.4.2 my example:

I created over-world portal X which created a nether portal NX.

later I built platform and "temple" near X and built a new portal Y (~ 30 blocks away) Y properly took me to NX however when entering NX It created a new over-world portal Z ~100 blocks to the west. completely unexpected. I tore down the new portal but every time I entered NX it would take me to the Z position.

so In the nether I tore down NX traveled far away to another portal we had that linked to a distant over-world portal (~300 blocks away in the nether). then went all the way back in the over-world and entered Y (to force it to create a new nether portal) new portal NY was positioned over top of NX and now links propely with Y . It's definitely seems like a bug that NX could not find and link into Y and created a portal so far away.

As Daedalus Young mentioned, this is not a real bug, it's just that when you create a overworld portal, the game will create the closest possible portal in relative coordinates in the nether, and it is not always possible (rare). His "fix" is also correct.

This is NOT a bug, and in fact, you should be happy about this, because the new portal that is created when you get back from the nether can be grieved to give you 12 free obsidian, and then just go to the nether and back and there you have more 12 obsidian ... free obsidian farm =p

As for the compass, no it does not point to your spawn point, it points to 0,0.

I would be willing to accept this errant behavior as "correct" if it could be explained why a portal that (a) already exists, and (b) is the originator of the nether portal, is not suitable for re-connection, and (c) in my experience, not even consistently, since it does SOMETIMES connect to it--it can't be suitable AND unsuitable. Free obsidian is not an excuse to leave a bug alone (still assuming it IS one).

And the compass, whether it points to the spawn or 0,0 or whatever should, at least, point to the SAME place all the time, and not shift when you return through a portal (until the program is reloaded)--this IS a bug, without question. Maybe not hugely important, but should be fixed.

Well, on the world where this happened to me, and as far as I am aware, this happens because every time you step thru a portal, the game looks for the closes possible portal and if the closest is (a) too far and (b) it's possible to create one closer, it WILL create a closer portal.

So, if when you created the portal, the nether portal was created somewhat far from where it "should", and this reads something like this: neither on open terrain so the game would create a floating portal exactly on the right coordinates, nor too far inside netherrack to create a cave exactly on the right coordinates, so in a not-perfect coordinate but in an already-existing cliff/plain in the nether, then the Nether portal would be created far from the optimal location.

Upon going back, the game checks the same, except this time it's possible to create a better portal, so it does.

I don't think this is really a bug, just a question of the game trying to reuse portals AND land when possible. Either it's hard coded to build portals always perfectly (where's the fun on that =p), or to build portals on the closest possible terrain (this is not possible, imagine if it is in the middle of lava, the closest possible terrain would be really far), so the compromise of either one of the another creates this effect.

In my world I did the math, found out that, indeed, the perfect place was floating above lave some 20m away, build a bridge/fort on the proper place and then built a new portal there ... and as expected, the issue was "solved" with it connecting to my original portal perfectly.

A possible solution is to link portals, but then again it's not entirely possible because of the 1/8 coordinate issue (hugely useful as to use the nether as a "fast travel" system)

As for the compass, Ever since 1.0 (which is when I started playing), compasses always pointed consistently to 0,0, so I don't know what happened in your case

Ok, so this Nether portal thing isn't a bug, that's cool, but Caio, what do you mean Compasses always consistently pointed to 0,0? The compass problem that I had never existed for me prior to this update, and it always pointed to the spawn. I am not sure what you are trying to say, but that never happened. Plus, it wouldn't make common sense, the spawn isn't necessarily at 0,0, so why would it point there? It would be simply be useless and unnecessary to make an item that does something like that.

hmm I think somewhere along the way, the original spawn point was always 0,0, but since it is now somewhat random, it isn't so. You are right, it points to your original spawn point (alas, it was once 0,0)

Nevertheless, my compass points to the same place always, and I have some maps I created in 1.1 and it points to the original spawn point too. I don't remember any upgrade breaking the compass!

I can see in my scenario how the portals may be working as described--though it still doesn't make sense that it's being inconsistent, but since it's recalculating each time...

The compass situation is related to the portal--every time I re-enter, it's off, to the same "new" point. Now that I think about it, it could be something to do with the compass being in the Nether...?

Although it might be a feature for some players (btw. obsidian isn't that rare), it is a bug.

I don't think that the player should have to calculate what the correct position of the portal is or the like. The game should calculate the correct position, so that using the nether portal NX (that was created by using the overworld portal N) leads the player to that overworld portal N.

I believe it's getting to a matter of preference, of perspective. I like how it is, because it is basically telling us: Portals are to go to the nether and back, they are not connected, if something goes wrong, adapt.

So IMHO, I love it, and I hope it stays this way

BTW while obsidian isn't rare, having a known place to spawn it beats getting lava to make it, also, you have to be more or less unlucky to get this issue anyway. I love calculating gates, because that way I can build my own fast-travel, with gates on each town/city, and then using them to move quickly between them. Without no math, that would be quite hard to do.

This has nothing to do with preference. It's a bug, a problem with the algorithm that calculates the positions of the portals.

For example, one may say a duplication bug is a nice feature, but it's not, it's a bug. However, this discussion isn't getting us anywhere.

It's interesting how you simply dismissed the fact it work as intended, and guarantees it's a bug. Well, if you have the final world, it is.

I for one like the FEATURE (since it is as intended) and would fell a loss if it were removed from the game.

The discussion was going somewhere, with each giving their opinions, until someone got in here being emphatic that his opinion rules it all. "It is a bug". Can't argue with statements so I leave for Mojang to decide either to leave the feature or not.

To be fair, Caio, you are the only one participating in this discussion that is insisting it is working as intended. I seriously doubt that it is--it isn't behaving in a logical manner; I can't bring myself to believe they specifically intended that a portal duplicate itself, and randomly at that. On the other hand, I don't necessarily think it's a malfunction, but an unintended consequence of how it's been written.

It should be fixed, or refined, or at least, made "official."

Official Minecraft Wiki reports the behaviour I described since BETA versions: http://www.minecraftwiki.net/wiki/Nether_Portal

The behavior is well know and long time players expect it to work that way, and it is not even considered a trivia or bug.

Now this is how you raise statements and not arguments. I'm out.

Daniel unless you can present a case using facts that portal behavior is not working as intended we have to assume that it is working as intended. For example present your case saying that overworld portal at coordinates X & Z and portal in nether at coords X & Z are not connecting.

Now some nutshell facts about how the portals work (or have prior to 1.4) so you can cross check your results:
~When you step into a portal the game look for a portal in the other dimension within 128 blocks of the relative coords.
~Each block in the nether = 8 blocks in the overworld
~Relative coords depends on which way you're traveling; if to the nether divide the X&Z coords by 8, if from the nether multiply the X&Z coords by 8.

Now an example situation:
Overworld portal at X=80,Z=80 however when you travel to the nether the nether side portal was relocated due to obstructing netherrack or a large lava area and instead of being at X=10,Z=10 it is at X=35,Z=12. When you step back through the portal to return to the overworld it looks for a portal within 128 blocks of overworld coordinates X=280,Z=96. Since your original portal was at X=80 that is more than 128 bocks away and so a new portal is created. As you can see the nether side portal being relocated by more than 16 blocks can make it not connect anymore to the overworld portal you came in from.

To me this never happened prior to 1.4, but if it did, I'd still think that this is not intended and should be "fixed" (what about deleting the obstructing netherrack and placing the portal normally).

Also we're just players and volunteers posting bugs, so I don't think that we have to prove that it's not working. (Mojang has to prove that it is working, because they made this great game.)

I'm big enough to admit when I'm wrong.

Apparently, what is being experienced here is the 2-in-1 effect, as follows:
"2-in-1 Nether Portals - It is possible to end up in a situation where a Nether Portal "randomly" places the player in 1 of 2 possible Normal World destination portals. This is simply because the Nether Portal has two effective coordinates as it is 2 blocks wide, say (X, Y, Z) on the left, and (X+1, Y, Z) on the right. If the player entered on the left side, (X, Y, Z) translates to (X*8, Y, Z*8) in the overworld and the game picks the portal closest to that. If the player entered on the right side, (X+1, Y, Z) translates to (X*8+8, Y, Z*8) and the game picks a portal closest to that point instead. This situation occurs when the Nether Portal's location is roughly equidistant between the 2 Normal World portals (within 8 blocks overworld distance difference)."

After further testing my situation, I have confirmed that this is the case.

However, the documentation references two overworld portals that ALREADY EXIST, and does NOT indicate that the effect will create a NEW overworld portal where only ONE exists—which is what has occurred in my situation. Otherwise, it is behaving exactly as described. So, could be a bug—as the OP stated, I haven't encountered this before 1.4.3—or could be an oversight in the documentation.

That said, the compass issue is definitely a bug.

Portals and the Nether were intended to be a fast travel system. However when they were introduced the implementation was broken.

Notch said this on his Tumblr shortly after on the 5th Nov 2010

• Attempted to fix the portal dupe bug where you could exit through a different (new) one than the one you entered through.

About the portals, it’s possible that two portals can lead to the same portal in the Nether. This is because the space down there is compressed by a factor of 8, and I haven’t come up with a good way to fix this yet.

I might just end up doing an explicit one-to-one binding between portal pairs, but that’s nontrivial as it should survive the portal being temporarily destroyed. If you TNT a portal then rebuild it, you’d expect it to still lead to the same place, right?

From: http://notch.tumblr.com/post/1486843146/minecraft-alpha-1-2-1-minecraft-server-0-2-3

As far as I can see this bug has been placed in the too hard basket ever since. It has not been fixed and now some players assume it is standard behaviour.

The same happened to me as well.
With the difference that my nether portal worked out to be a dual portal.
One half led back, other half led in mid-air above a lake, at least 15m above...

I though I was insane / the thing was random before I realized what's happening.

(Also I spawned under water in that world when I created it)

It happen to me too.
I build a portal to the nether, i enter on it, when i pass to the portal of the nether, i leave nether by other portal created in the overworld with a 40 blocks of space between the original portal.

It happens in 1.6.1

Got this problem in Snapshot 14w27b.

Got this problem in 1.8 as well.
Home portal - XYZ: -247.554/63.5/164.097
Portal in Nether - XYZ: -11.636/36.0/27.935
Random Portal - XYZ: -104.870/63.0/227.804

@Pedro it's supposed to be that way according to Mojang 😞

I dont see how there is not a bug to this.

On a Realm my portal worked fine several times. Someone else used it and suddenly it was throwing up portals to random locations on trips back to overworld, underground, nearby on a beach. if it was because the first portal was off and so that the portal back wasn't at the right alignment why did it work fine for me several trips back and forth but then suddenly stop working and start creating new portals?

Fixed it by dying in Nether after breaking portal and rewalking through overland portal, it made a new portal on top of the cobble building and that one has yet to make a new one back. But previous to that just breaking and reusing same spot had same results, so I agree that it seems like the idea that the relocating to best nearest spot caused it but why did it work fine for awhile before starting the behavior?

Apologies if this is duplicate information from an existing comment.

Here's the actual problem: When migrating an existing map from 1.7 to 1.8, not all of the existing portals stay lit... or if they do, they don't stay fully lit. (By lit I mean active; I wish I'd taken screenshots of portals with only one or two squares active.) Thus, when you step from the Nether to what you think is an existing, active portal, the game will find the obsidian from the previous portal, now deactivated, which blocks the spawn of a new active portal. As a result, a new active portal is spawned, sometimes right near the previous portal, sometimes further away.

Again, apologies if this comment duplicates a previous comment.

I am having this issue in snapshot 15w43c. Every time I use the portal the game autospawned in the Nether, it creates a new portal in the Overworld. When I break the new Overworld portal and repeat the process, another new portal is generated near the same spot (in the Overworld).

I just had this issue in snapshot 15w43c. Same as the description at the top. I've done it about six times now and it is quite obnoxious.

We know that it is in the game, but Mojang has decided that it doesn't see it as a bug.

Kaleb the very first response to the OP above is still correct, to my knowledge nothing has changed with portals in the 1.9 snapshots. That is how portals work. They aren't inherently linked, basically when you walk into a portal it looks for another portal within 128 blocks of the relative coordinates of the portal you walked into in the other world. If no portal is found it places one in the nearest location that meets the criteria. Sometimes when you travel to the nether there is no suitable place very near the relative coordinates of the portal in the overworld, so the location of portal in the nether is moved quite a bit. Due to how 1 block in the nether is equal to 8 blocks in the overworld if the portal location is moved more than 16 blocks from the relative coordinates it will no longer be within the 128 block search radius of the over world portal and so a new portal will be created in the overworld. This is because 16*8=128, thus more than 16 blocks of difference on the nether side means it will be out of range of the portal you traveled from in the overworld. You can read more details about this on the wiki ( http://minecraft.gamepedia.com/Nether_portal )

This can be fixed by manually moving the portal in the nether. You will need to get the X and Z coordinates of your portal in the overworld and then divide those coordinates by 8 (make sure to pay attention to whether they are negative numbers). Then go to the nether and build a new portal at the coordinates you calculated. You will likely have to build out over a lava lake or mine a room out in a large formation of netherack which were the causes for your portal to be displaced in the first place.

If after making sure you understand normal portal behavior you discover this is not your issue, I recommend you start a new bug report and lay out in detail how what you're experiencing is deviating from how portals are supposed to work. Good Luck!