When a Nether Fortress attempts to generate the external broken bridge structure (represented by the ID "NeBEF" in Fortress.dat), and the structure is surrounded by Netherrack, no structure generates inside the bounding box. The fortress simply ends at a wall of Netherrack.
Seed: 2726140590913983575
Go to Nether
Gamemode spectator
Tp to -206 66 171
inside Netherack, no structure
face North, end of bridge can be seen
Tp to -58 66 139
outside Netherrack, structure appears correctly
Linked issues
relates to 4
MC-216207
Stronghold corridors commonly end in stone
Open
MC-193936
The tops of stairs above nether fortress wart rooms can generate obstructed
Open
MC-216221
Nether fortress bridges that generate through terrain don't have proper roofs
Open
MC-216224
Nether fortress corridors can abruptly end without a "broken bridge" structure
Open
Attachments
Comments 10
I have checked this at multiple locations by teleporting to the middle of the bounding box while in spectator mode. I used an NBT editor to obtain the coordinates for these bounding boxes by looking up a sample of fortress segments with the id "NeBEF".
If the bridge end is outside netherrack, it generates normally inside its bounding box. If the bridge end is inside netherrack, all that is found inside the bounding box is netherrack. No bridge end structure is seen here; the bridge appears to end before the actual end segment. If you go outside to where the walkway ends and look at the netherrack at the apparent end, its coordinates coincide with the bounding box of the missing segment.
After closer examination, I have determined that the missing segment IS being generated, but the netherrack is not being replaced by air blocks. I suspect the cause is: Missing structure void blocks.
I have added three screenshots. One shows a normal structure with the bounding box encased in white concrete. One shows the view inside a structure inside netherrack - the end of the bridge can be seen nearby. The third shows the missing end, with netherrack at the edge of the bounding box replaced by white glass. In the last screenshot, the structure can be seen continuing inside the netherrack.
Missing structure void blocks.
Nether fortresses don’t use structure files, they are from before that time.
And even if it was, then it’s a wrong statement anyway, as it’s supposed to be air; structure voids are the ones that prevent overwriting existing blocks.
Rechecked in 1.13.1.
The location of Nether fortresses are different in this version and the location of a broken bridge in Netherrack in the original steps to reproduce are no longer valid. A broken bridge inside Netherrack can be found near -581 73 155.
As Pokechu22 points out, the broken bridge generates normally inside netherrack but it cannot be seen because the netherrack isn't removed to expose it.
It is still happening, but after reviewing this I would say this isn't an issue that needs fixing. I recommend that this bug report be closed.
Broken bridge pieces can successfully generate inside netherrack, so I think this can be closed.
There is a similar problem in MC-216224 - sometimes they won't generate at all, no matter if surrounded by netherrack or not.
Closing this as Working as Intended would be a suitable resolution.
The broken bridge pieces appear to be buggy because they are not generating with air blocks (unlike adjacent bridge pieces). That isn't really a problem.
(haven't tried out the world yet) If I recall correctly, the bridge itself usually tunnels through netherrack correctly, but the jagged end of the bridge does not tunnel through netherrack. Is it the end or a complete bridge you're seeing?