It will render other maps fine. The custom nether maps it gives and error. I don't understand the error. It seems to stop repeatedly at tile 3800 on the netherroof map only.

[dynmap] Exception during render job: world=world_nether, map=org.dynmap.hdmap.HDMap@61a7f30b
Minecraft 1.15.2
Version: core=3.0-beta-10-257
plugin=3.0-beta-10-257

All other maps work fine.
https://pastebin.com/YVgans7x configuration.txt
https://pastebin.com/19aFknPb worlds.txt
https://pastebin.com/gQfbw0LU custom-nether-hires.txt
https://pastebin.com/HrmrjyDV custom-perspectives.txt

I think I have everything there you may need. I bet it is something simple I am missing.

Did you try to look at the chunk with mcedit? Maybe you can give the devs some data from there.

It's 1.15 and I don't believe mcedit works with it unless you know how to and wish to disclose. :) I would happily, though, if it worked.

Also, I verified disc space just to make sure. I even moved the whole server over to a new server to make sure.

@otse I also wondered how you could tell which chunk* it is?

sorry, fixed the sentence to makes sense @otse lol my fault :)

Actually, just looked and got more errors when I just tried to run it again...

[18:00:19] [Dynmap Render Thread/ERROR]: [dynmap] Exception during render job: world=Bees Update_nether, map=org.dynmap.hdmap.HDMap@1b84dbc0
[18:00:19] [Dynmap Render Thread/WARN]: java.lang.ArrayIndexOutOfBoundsException: 16
[18:00:19] [Dynmap Render Thread/WARN]: at org.dynmap.bukkit.helper.v115.MapChunkCache115$NBTSnapshot.getBlockType(MapChunkCache115.java:264)
[18:00:19] [Dynmap Render Thread/WARN]: at org.dynmap.bukkit.helper.AbstractMapChunkCache$BasetMapIterator.getBlockType(AbstractMapChunkCache.java:138)
[18:00:19] [Dynmap Render Thread/WARN]: at org.dynmap.hdmap.IsoHDPerspective.render(IsoHDPerspective.java:1260)
[18:00:19] [Dynmap Render Thread/WARN]: at org.dynmap.hdmap.HDMapTile.render(HDMapTile.java:79)
[18:00:19] [Dynmap Render Thread/WARN]: at org.dynmap.MapManager$FullWorldRenderState.processTile(MapManager.java:773)
[18:00:19] [Dynmap Render Thread/WARN]: at org.dynmap.MapManager$FullWorldRenderState.run(MapManager.java:689)
[18:00:19] [Dynmap Render Thread/WARN]: at org.dynmap.MapManager$DynmapScheduledThreadPoolExecutor$1.run(MapManager.java:198)
[18:00:19] [Dynmap Render Thread/WARN]: at org.dynmap.MapManager$DynmapScheduledThreadPoolExecutor$2.run(MapManager.java:214)
[18:00:19] [Dynmap Render Thread/WARN]: at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
[18:00:19] [Dynmap Render Thread/WARN]: at java.util.concurrent.FutureTask.run(FutureTask.java:266)
[18:00:19] [Dynmap Render Thread/WARN]: at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180)
[18:00:19] [Dynmap Render Thread/WARN]: at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293)
[18:00:19] [Dynmap Render Thread/WARN]: at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
[18:00:19] [Dynmap Render Thread/WARN]: at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
[18:00:19] [Dynmap Render Thread/WARN]: at java.lang.Thread.run(Thread.java:748)

Here is a link to my nether file zipped.

https://drive.google.com/open?id=1yWyEAM4iUA4p8LLRX9dTTpl1a3VUbJw8

We seem to be having a similar issue with Dynmap-3.0-RC1-spigot.

[Dynmap Render Thread/ERROR]: [dynmap] Exception during render job: world=world_nether, map=org.dynmap.hdmap.HDMap@310f7899
[Dynmap Render Thread/WARN]: java.lang.ArrayIndexOutOfBoundsException: 16
[Dynmap Render Thread/WARN]:         at org.dynmap.bukkit.helper.v115.MapChunkCache115$NBTSnapshot.getBlockType(MapChunkCache115.java:265)
[Dynmap Render Thread/WARN]:         at org.dynmap.bukkit.helper.AbstractMapChunkCache$BasetMapIterator.getBlockType(AbstractMapChunkCache.java:138)
[Dynmap Render Thread/WARN]:         at org.dynmap.hdmap.IsoHDPerspective.render(IsoHDPerspective.java:1260)
[Dynmap Render Thread/WARN]:         at org.dynmap.hdmap.HDMapTile.render(HDMapTile.java:79)
[Dynmap Render Thread/WARN]:         at org.dynmap.MapManager$FullWorldRenderState.processTile(MapManager.java:773)
[Dynmap Render Thread/WARN]:         at org.dynmap.MapManager$FullWorldRenderState.run(MapManager.java:663)
[Dynmap Render Thread/WARN]:         at org.dynmap.MapManager$DynmapScheduledThreadPoolExecutor$2.run(MapManager.java:214)
[Dynmap Render Thread/WARN]:         at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
[Dynmap Render Thread/WARN]:         at java.util.concurrent.FutureTask.run(FutureTask.java:266)
[Dynmap Render Thread/WARN]:         at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180)
[Dynmap Render Thread/WARN]:         at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293)
[Dynmap Render Thread/WARN]:         at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
[Dynmap Render Thread/WARN]:         at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
[Dynmap Render Thread/WARN]:         at java.lang.Thread.run(Thread.java:748)

I have added a flat and a surface map to the default nether map section. These two new maps render from Y-level 128 to 256 so we can see on top of the Bedrock ceiling.

Worlds configuration:

    -   class: org.dynmap.hdmap.HDMap
        name: flat_top
        title: Flat_Top
        icon: images/block_flat.png
        prefix: flat_top
        perspective: nether_top_map_scale16
        shader: stdtexture
        lighting: nethershadows
        background: '#300806'
        mapzoomin: 5
    -   class: org.dynmap.hdmap.HDMap
        name: nether_top
        title: Surface_Top
        icon: images/block_nether.png
        prefix: nether_top
        perspective: nether_iso_SE_scale16
        shader: stdtexture
        lighting: nethershadows
        background: '#300806'
        mapzoomin: 3
        boostzoom: 2

Custom perspectives:

  - class: org.dynmap.hdmap.IsoHDPerspective
    name: nether_top_map_scale16
    maximumheight: 256
    minimumheight: 128
    inclination: 90
    scale: 16
    azimuth: 180
  - class: org.dynmap.hdmap.IsoHDPerspective
    name: nether_iso_SE_scale16
    maximumheight: 256
    minimumheight: 128
    azimuth: 135
    inclination: 30
    scale: 16

It looks like changing maximumheigh to 255 instead of 256 solved our issue. I have no idea why I put 256 there since Y-levels only go from 0-255 in unmodded Minecraft. Definitely user error. But perhaps a check on max Y-level instead of a crash might be something to add?

Interesting. Same with mine. It's still processing but it continued past its previous limit.

Easy to do as the build limit is 256, you'd think 256 is the limit. I did the same with mine. Seems like an error in programming but I'm am not a programmer.

dang, I can't believe that was the issue. It appears to have rendered fine.