chore(paper): update migration guide

Author: Strokkur424

src/content/docs/paper/admin/getting-started/migration.md

@@ -16,33 +16,6 @@ See our [Backup Guide](/paper/updating#step-1-backup) for more information.
 
 ## Migrating to Paper
 
-### From CraftBukkit or Spigot
-
-It's easy to migrate from CraftBukkit or Spigot to Paper. Follow the steps below.
-
-1. Stop your server if it is running, and create a full backup.
-2. Download Paper from [our downloads page](https://papermc.io/downloads).
-3. Rename the downloaded file to match the name specified in the [start command](/paper/getting-started#running-the-server).
-4. Replace your existing JAR file with your freshly downloaded Paper JAR.
-5. Start your new server.
-
-Up until 1.20.5, Paper retained full compatibility with all Spigot plugins. However, plugins using Spigot API
-added **after** 1.20.5 version will not work. Such plugins may often provide Paper-compatible builds. If they
-do not do that, you will need to look for alternatives. However, nowadays most plugins are built and tested
-against Paper, so you typically will not encounter incompatible plugins.
-
-:::note
-
-Your new Paper server will still use [`bukkit.yml`](/paper/reference/bukkit-configuration)
-and [`spigot.yml`](/paper/reference/spigot-configuration).
-New configuration options can be found in [`config/paper-global.yml`](/paper/reference/global-configuration)
-and [`config/paper-world-defaults.yml`](/paper/reference/world-configuration).
-
-:::
-
-If you have any issues migrating from CraftBukkit or Spigot, do not hesitate to reach out for
-support on [our Discord server](https://discord.gg/papermc) (`#paper-help` channel).
-
 ### From Vanilla
 
 When migrating to Paper from Vanilla, the way worlds are stored will automatically be changed.
@@ -52,7 +25,8 @@ closely, as manual changes will be required.
 1. Stop your Vanilla server if it is running, and create a full backup.
 2. Download Paper from [our downloads page](https://papermc.io/downloads) and replace your Vanilla
    server JAR with your freshly downloaded Paper JAR.
-3. Rename the downloaded file to match the name specified in the [start command](/paper/getting-started#running-the-server).
+3. Rename the downloaded file to match the name specified in
+   the [start command](/paper/getting-started#running-the-server).
 4. Start your new Paper server.
 
 You have now successfully migrated to Paper. If you encounter any issues, do not hesitate to reach
@@ -69,10 +43,59 @@ Additionally, note that Paper does not support Fabric or Forge mods. You will ne
 replacements. Any hybrids that attempt to support both mods and plugins are fundamentally flawed and
 not recommended for use.
 
+### From Spigot/CraftBukkit
+
+Spigot and CraftBukkit modify the Vanilla world directory structure, making a direct migration
+fundamentally impossible. If you wish to migrate from Spigot/CraftBukkit anyway, you will
+first need to **migrate from Spigot/CraftBukkit to Vanilla**, after which you can safely follow
+the [Vanilla Migration Guide](#from-vanilla). For instructions on how to do this, please
+refer to the Spigot documentation.
+
 ## Migrating from Paper
 
 ### To Vanilla
 
+Because Paper shares a similar world structure to Vanilla, all you need to do is move around some files.
+The following list shows which files you will need to move where. **Before you move around any files,
+make sure your server is fully stopped**.
+
+:::note
+
+These steps assume a `level-name` (as set in `server.properties`) of `world`. If this is not the
+case for you, replace `world` with your `level-name` for all steps below.
+
+:::
+
+The following files will need to be moved **from** `world/dimensions/minecraft/overworld/data/minecraft/`
+**into** `world/data/minecraft/`:
+
+- `game_rules.dat`
+- `scheduled_events.dat`
+- `wandering_trader.dat`
+- `weather.dat`
+- `world_gen_settings.dat`
+
+After you have moved these files, you can now replace the Paper server JAR with a Vanilla server JAR
+and start your Vanilla server!
+
+### To Fabric/Forge
+
+Because both Fabric and Forge use the same directory structure for world storage as Vanilla, follow
+the [Vanilla Migration Guide](#to-vanilla) for this process. Note that neither Fabric nor Forge will
+support Paper plugins! You will be required to find replacement mods.
+
+## Other Migration
+
+:::caution
+
+The guides below display outdated information no longer relevant for modern Paper servers. They are
+kept for historical purposes and people still using older versions. Please note that you will
+**not receive support for using outdated versions.**
+
+:::
+
+### To Vanilla (pre 26.1)
+
 Because Paper stores worlds slightly differently than Vanilla, manual work is required to migrate.
 If these steps are not taken, your nether and end will look like they have been reset. Don't worry!
 Even if this has happened, you haven't lost any data. The Vanilla server just doesn't know where to
@@ -81,7 +104,7 @@ find it.
 Here is a chart to show the difference between how Vanilla and Paper store worlds.
 
 | Server Software | Overworld | Nether                | End                   |
-| --------------- | --------- | --------------------- | --------------------- |
+|-----------------|-----------|-----------------------|-----------------------|
 | Vanilla         | `/world`  | `/world/DIM-1`        | `/world/DIM1`         |
 | Paper           | `/world`  | `/world_nether/DIM-1` | `/world_the_end/DIM1` |
 
@@ -104,14 +127,12 @@ case for you, replace `world` with your `level-name` for all steps below.
 6. Replace your Paper JAR with a Vanilla server JAR.
 7. Start your Vanilla server.
 
-### To CraftBukkit or Spigot
+### To/From CraftBukkit or Spigot
 
-Paper does **not** support migration to either CraftBukkit or Spigot! While you may find success
-(both CraftBukkit and Spigot use the same directory structure as Paper), **do not** reach out for
+Paper does **not** support migration from or to either CraftBukkit or Spigot!
+While you may find success, **do not** reach out for
 support with issues you encounter and note that data loss is possible.
 
-### To Fabric/Forge
-
-Because both Fabric and Forge use the same directory structure for world storage as Vanilla, follow
-the [Vanilla Migration Guide](#to-vanilla) for this process. Note that neither Fabric nor Forge will
-support Paper plugins! You will be required to find replacement mods.
+Historically, migrating from Spigot to Paper was possible due to a shared directory structure
+(`1.21.11` and older), however since `26.1`, Paper's world directory structure has been
+altered to more closely match Vanilla, which made migrating from or to Spigot/CraftBukkit no longer possible.