Minecraft - How to change the world seed with NBTUtil

Tiago Stoco -

Follow the previous article to compile the NBTUtil binary.

Run the binary as follow pointing to your level.dat file using the flag --printtree to inspect the file and find the seed entries.

mono NBTUtil.exe --path=level.dat/Data/WorldGenSettings --printtree
WARNING: The runtime version supported by this application is unavailable.
Using default runtime: v4.0.30319
 + WorldGenSettings: 4 entries
   + bonus_chest: 0
   + generate_features: 1
   + seed: 3565334308987963721
   + dimensions: 3 entries
     + minecraft:overworld: 2 entries
     | + type: minecraft:overworld
     | + generator: 4 entries
     |   + seed: 3565334308987963721
     |   + settings: minecraft:overworld
     |   + type: minecraft:noise
     |   + biome_source: 2 entries
     |     + preset: minecraft:overworld
     |     + type: minecraft:multi_noise
     + minecraft:the_end: 2 entries
     | + type: minecraft:the_end
     | + generator: 4 entries
     |   + seed: 3565334308987963721
     |   + settings: minecraft:end
     |   + type: minecraft:noise
     |   + biome_source: 2 entries
     |     + seed: 3565334308987963721
     |     + type: minecraft:the_end
     + minecraft:the_nether: 2 entries
       + type: minecraft:the_nether
       + generator: 4 entries
         + seed: 3565334308987963721
         + settings: minecraft:nether
         + type: minecraft:noise
         + biome_source: 2 entries
           + preset: minecraft:nether
           + type: minecraft:multi_noise
/nbtutil/level.dat/Data/WorldGenSettings: OK
Operation complete.  Nodes succeeded: 1  Nodes failed: 0

As you can see there are 5 entries with the map seed and we need to change every single using the commands below :

mono NBTUtil.exe --path=level.dat/Data/WorldGenSettings/seed --setvalue=7360393597478526904
General seed value.
mono NBTUtil.exe --path=level.dat/Data/WorldGenSettings/dimensions/minecraft:overworld/generator/seed --setvalue=7360393597478526904
Overworld seed value.
mono NBTUtil.exe --path=level.dat/Data/WorldGenSettings/dimensions/minecraft:the_end/generator/seed --setvalue=7360393597478526904
The End general seed value.
mono NBTUtil.exe --path=level.dat/Data/WorldGenSettings/dimensions/minecraft:the_end/generator/biome_source/seed --setvalue=7360393597478526904
The End sub seed value.
mono NBTUtil.exe --path=level.dat/Data/WorldGenSettings/dimensions/minecraft:the_nether/generator/seed --setvalue=7360393597478526904
Nether seed value.

After the changes the file should look like the below:

mono NBTUtil.exe --path=level.dat/Data/WorldGenSettings --printtree
WARNING: The runtime version supported by this application is unavailable.
Using default runtime: v4.0.30319
 + WorldGenSettings: 4 entries
   + bonus_chest: 0
   + generate_features: 1
   + seed: 7360393597478526904
   + dimensions: 3 entries
     + minecraft:overworld: 2 entries
     | + type: minecraft:overworld
     | + generator: 4 entries
     |   + seed: 7360393597478526904
     |   + settings: minecraft:overworld
     |   + type: minecraft:noise
     |   + biome_source: 2 entries
     |     + preset: minecraft:overworld
     |     + type: minecraft:multi_noise
     + minecraft:the_end: 2 entries
     | + type: minecraft:the_end
     | + generator: 4 entries
     |   + seed: 7360393597478526904
     |   + settings: minecraft:end
     |   + type: minecraft:noise
     |   + biome_source: 2 entries
     |     + seed: 7360393597478526904
     |     + type: minecraft:the_end
     + minecraft:the_nether: 2 entries
       + type: minecraft:the_nether
       + generator: 4 entries
         + seed: 7360393597478526904
         + settings: minecraft:nether
         + type: minecraft:noise
         + biome_source: 2 entries
           + preset: minecraft:nether
           + type: minecraft:multi_noise
/nbtutil/level.dat/Data/WorldGenSettings: OK
Operation complete.  Nodes succeeded: 1  Nodes failed: 0

You can now start your server and run the /seed command to make sure its returning the new seed value.