Troubleshooting

Fix "Failed to load datapacks" and "Overworld settings missing"

A world keeps a list of the datapacks it was created with. Terrain packs such as Terralith go further: they change how the Overworld is generated, and the world's generation settings point to their biomes by name. When such a pack or mod is gone, the server cannot rebuild those settings, and it refuses to start rather than guess.

The world itself is still on the disk, chunk for chunk. This guide shows how to tell what is missing from the lines in the console, how to put it back, and what to do when the world simply comes from a newer Minecraft version.

In short

"Failed to load datapacks, can't proceed with server load" means the world refers to something the server cannot find: a datapack or mod it was generated with, or settings saved by a newer Minecraft version. The lines just above it say which. Put the missing pack or mod back, or run the version that last saved the world, and it loads again with nothing lost.

Read the lines above the error

Open the Console tab after the failed start. The error itself only says the server gave up; the reason is in the lines just before it. A server that lost Terralith, which was installed as a mod, shows lines like these:

[ServerMain/WARN]: Missing data pack mod:terralith
[ServerMain/WARN]: Failed to load datapacks, can't proceed with server load. You can either fix your datapacks or reset to vanilla with --safeMode
java.util.concurrent.ExecutionException: java.lang.IllegalStateException: Overworld settings missing

Line above the error	What is gone	Where to look
`Missing data pack mod:terralith`	A mod the world was created with	Put it back, see below
`Missing data pack file/Terralith_1.21.11_v2.6.0.zip`	A datapack zip from `world/datapacks`	Put it back, see below
`No key dimensions in MapLike[{}]; No key seed in MapLike[{}]`	Nothing; the world was saved by a newer Minecraft version	No key dimensions, further down
`Missing data pack paper` or `Missing data pack fabric`	Nothing that matters; the world last ran on other server software	Read the next line instead

A Missing data pack line on its own is only a warning. Packs that add recipes or loot can go missing without any crash. It only stops the server when the pack shaped the world, which is what Overworld settings missing tells you.

Put the missing pack or mod back

The fix is to give the world what it was made with, in the same version. The name in the line tells you which: file/Terralith_1.21.11_v2.6.0.zip is Terralith 2.6.0 for Minecraft 1.21.11.

A file/ pack

Stop the server.
Download exactly the version named in the line.
On the Files tab, open world/datapacks and use Upload to put the zip there as it is. Do not unpack it.
Start the server. When the console reaches Done, the world is back.

A mod: pack

Open the Mods tab.
Under Verified Modrinth catalog, search for the mod after mod:, here terralith, and click Verify & install.
Start the server and check the Console for Done.

On Paper and Purpur the main world folder is the one to use, world/datapacks, not world_nether or world_the_end.

Terrain that was generated with the pack stays as it was. To stop using the pack you need a new world, because the old one keeps depending on it; reset your world shows how.

No key dimensions in MapLike: a world from a newer version

java.util.concurrent.ExecutionException: java.lang.IllegalStateException: No key dimensions in MapLike[{}]; No key seed in MapLike[{}]

This line appears when a world last saved by Minecraft 26.1 or newer is started on 1.21 or older. From 26.1 on, the seed and the dimensions are stored in a file of their own, world_gen_settings.dat, instead of in level.dat. An older server looks in level.dat, finds no seed and no dimensions, and stops.

We saw it on a server set to 1.21.11 with a world from 26.2. Minecraft only converts worlds forward, so there are two ways out:

Set the server to the version that last saved the world, in this case 26.2. Change the server version shows where.
Restore a backup from before the world was opened in the newer version, on the Backups tab.

Before you try --safeMode

The error suggests --safeMode, which starts the server with only the vanilla datapack. That helps when a broken pack stops everything while the world does not depend on it. In the cases above the world does depend on what is missing, so putting the pack, mod or version back is the way to keep it as it was.

Whatever you try, make a backup on the Backups tab first. Back up and restore your server explains how.

Questions from Minecraft server owners

What does Failed to load datapacks, can't proceed with server load mean?

The world needs a datapack, mod or newer Minecraft version that the server does not have, so it stops before loading. The lines just above the error say what is missing.

Is my world gone after Overworld settings missing?

No. Every chunk is still there. The server only lacks the pack or mod the world was generated with. Put it back in the same version and the world loads.

Can I remove Terralith from an existing world?

Not without trouble. The world's settings refer to Terralith's biomes, so it stops loading. Keep the pack for that world, or start a new world without it.

What does No key dimensions in MapLike mean?

The world was last saved by Minecraft 26.1 or newer, and the server runs an older version. Run the newer version again, or restore a backup from before the upgrade.

Is Missing data pack paper a problem?

Not on its own. It means the world last ran on Paper. Look at the lines after it for the real cause.

Checked against Paper 1.21.11, Fabric and NeoForge server logs from our platform, November 2026. Written by the Cheapest Minecraft Hosting team, first published 8 November 2026, updated 8 November 2026.