Overworld Portals link to same portal

This happens in the non beta version in the realms as well. But my bug, I can go over 1000 blocks away in the over world and when I enter the portal it takes me to the portal that was created first in the nether, then when I come back it puts me in a new portal. 

Me too Nathan - I tested it out and even if it takes me to "new" nether and I get brought back to the "same" overworld location - it was always many blocks away and never from the same portal I built 

[Helper] Umija5859M - you are entirely wrong - this is a NEW BUG - I am VERY aware of how to set up portals correctly, I have been playing for years- this is WRONG this is NOT a previously resolved issue from 2018 - this is a NEW BUG!!!!!! as of Beta 1.16.100.51 - PLEASE UN-RESOLVE THIS TICKET IT IS NOT THE SAME AS MCPE 39609

I will ask for this to be investigated further. However, please avoid "shouting" by use of ALL CAPS etc. We are all just volunteers who are trying to help.

It would be helpful if you could list the exact XYZ coordinates of your portals (at the time the player enters/exits) and how they currently connect in the summary to make it easier for someone to check against the expected behavior.

Thanks for the screenshots. In the example in images 4 and 5, it looks as though it possibly should have generated a new portal around -218~ 351, which would be more than 136 blocks from the existing portal you ended up at.
In your world, are there any large obstructions or dangerous areas around -218 ~ 351, such as a large amount of netherrack, or a lava lake?

Apologies for the "shouting" - I wanted to make it very clear that this is a new bug that wasn't related to the 2018 one - nothing against you personally at all - I just didn't want it to be missed

Seed is: 568399557

Original Portal: -2168, 70, 1816  ~~ this leads to -255, 39, 227 in the Nether. When returning through the same portal in the nether, I end up at -2036, 71, 1819 which is 128 blocks away from my original portal

Second Portal:  -1740, 126, 2811, I ended up in  -210, 81, 444,  - instead of the expected -217, ~~ 351 and when I returned through the portal came out at -1688, 71, 3564

Mega Spud - no there isn't anything like that nearby - it should have brought me out directly into the portal I built so I don't know why it thinks it needs to transport me 100+ blocks (almost 1000 in the second portal...) away from the portal I built...

I'm going to assume that only the "Original Portal -2168 70 1816" and the "Second Portal -1740 126 2811" were created by the player, that all other mentioned portals were created by the game, and that there are no other portals in the area.

For "Original Portal":

OW -2168 70 1816 corresponds to N -271 70 227
so the N -255 39 227 portal is well inside the search range.

N -255 39 227 corresponds to OW -2040 39 1816
the generated portal at OW -2036 71 1819 is very close
the search range for that is X -2176 to -1905 | Z 1680 to 1951
the Original Portal is right at the edge of the range and if you happen to have been at X = -254 when you entered the portal instead of -255, the Original Portal would be outside the X search range of -2160 to -1889.

For "Second Portal"

OW -1740 126 2811 corresponds to N -217 126 351 as you noted.
the search range for that is X -352 to 81 | Z 208 to 479
the generated portal at N -210 84 444 is inside the range though somewhat farther away than might be expected. It's hard to say how the game decides where to place the generated portal. Since the Y coordinate was near the top of the nether it probably had to search farther away to find a suitable spot.

N -210 84 444 corresponds to OW -1680 84 3552
the search range for that is X -1808 to -1537 | Z 3424 to 3695
your Second Portal at -1740 126 2811 is outside this search range, so the game created a new portal

If you find something wrong with my calculations please let me know. Otherwise, the behavior seems as expected, though it is possible that there were some changes in the game between versions that cause it to work slightly differently than before.

As before, the best way to manage portals is to build the nether side portal at the exact corresponding (at least X and Z) coordinates and to remove the game-generated portals.

Thank you for responding so thoroughly!!

 Your assumptions and calculations I believe are correct

 however

 The issue I have is, if I create a portal in the overworld in a safe place, travel to the nether through that portal, then return to the overworld through that exact same portal, I should come out of the portal I originally built? But I have been returning through the exact same portal and being relocated many blocks away for seemingly no valid reason? The game has no need to relocate me to a different portal if I am travelling through a portal I have set up myself (with no other portals around - this was pre the second portal I created to test it later)

So whether or not I build an overworld or nether portal first, provided they are the only portals within that “chunk”, I should only ever return through those portals? Not an entirely new one? At least this was the case pre 1.16.100.51 whereby I could expect to go through a portal and return to the exact same portal as I left in? This surely must be a bug- the game has never translocated portals before - usually the discrepancies between the coordinates happens if as you said, there is a big lava lake or the ocean at the “requested” opposing coordinates so the game adjusts for that... but otherwise it would generate in the exact location and you could travel back and forth without creating more portals elsewhere or ending up in totally different locations (ie more than a few blocks of the calculations after allowing for any obstructions of which in this case there aren’t any) 

I just can’t believe that this is an intentional design by Mojang as it makes no sense 

I assume videos or gifs cannot be posted here? Otherwise I would do a short video to explain the pictures more clearly as it’s very difficult to communicate this issue with just pictures

When traveling from Nether to Overworld you will not necessarily come back to the original portal depending on how far away the one on the Nether side was generated. In your case, the first generated portal is right at the edge of the range needed to return you to the original overworld portal. Your best solution would be to move the portal on the nether side to -271 ~ 227 and this should always link back to your original portal.

You can post a video on YouTube and share the link here if you like.

Cannot reproduce in 1.16.20

This ticket is being resolved and linked as a duplicate of MCPE-39609. Based on analysis of the portal coordinates, it is working as intended.

@unknown: Your assumptions are incorrect as follows:

• Assumption: If portal O1 in the Overworld teleports you to portal N1 in the Nether, then portal N1 should teleport you to portal O1. This is false. A portal in the Nether teleports you to the nearest Overworld portal that is within 128 blocks of the N1 coordinates (X and Z only) multiplied by 8. (From now on, I will call such coordinates the "nominal coordinates in the Overworld", and for Overworld coordinates divided by 8, the "nominal coordinates in the Nether".)

• Assumption: There is no valid reason to teleport you to a different portal in the Overworld from the one you originally built. This is false. There are at least three situations that will cause you to go to a different portal: (a) The original Overworld portal no longer exists (broken, extinguished); (b) The original portal is more than 128 blocks away from the nominal coordinates; or (c) Another portal was closer to the nominal coordinates in the Overworld. (A) can happen when another player breaks your portal (perhaps a prank) or, rarely, when water flows into it unexpectedly. (B) happens simply because somebody built another portal. (C) most often happens because when you entered the Overworld portal, the game couldn't find a portal within 128 blocks of the nominal coordinates in the Nether, so it had to create one. but it was not able to create one at those coordinates because there wasn't anywhere safe there, at any Y level. Usually, that means there was a solid mountain of netherrack there, extending from bedrock to the Nether ceiling.

• Assumption: You are being relocated for no valid reason. I'm explaining the valid reasons now.

• Assumption: Portal linking has something to do with corresponding chunks. This is false. Linking is based on the 1:8 scale ratio of Nether to Overworld coordinates, rescaling the coordinates of the lowest portal block you entered. If there is no portal at that position in the destination dimension, the game searches up to 128 blocks in any direction for portals and chooses the nearest one, or if none are found it generates a new portal at the closest point it can to the rescaled coordinates. Chunk boundaries do not come into consideration.

• Assumption: It didn't work this way prior to 1.16.100.51. This is false. It has always worked this way in both Java and (after bug fixes years ago) Bedrock. You probably just never encountered any of the exceptions I listed above until recently (but other people did, and that's why this has been reported many times before)

• Assumption: This .surely must be a bug. Maybe, but you would need to prove it by calculating the nominal coordinates in the Nether for the Overworld portal's coordinates, then giving us a screenshot showing that there's nothing there in the Nether that would prevent the game being able to generate a portal. We have had a lot of reports like yours claiming there's a bug, but for 3 years nobody has been able to prove it yet. If you think you can, please give us your world seed, the coordinates where you built your Overworld portal, and the coordinates of the portal where you returned from the Nether.

• Assumption: Videos and gifs cannot be posted here. This is false, but there is a 10 MB size limit that might have rejected your attempt if you tried. You could try recording it at a lower resolution, or you could break it up into multiple shorter videos, or you could store it on a file sharing service (e.g. OneDrive) and give us a link.