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To edit bukkit.yml safely, stop the Minecraft server, open the file in the server’s root directory (or your host’s Files tab), change the YAML values, save the file, and start the server again. The restart is required for the new configuration to load.
This guide shows where the file is, how to edit it on a self-hosted or hosted server, what the important Paper settings mean, and how to recover from common YAML and performance problems. The exact keys and defaults can differ between Bukkit-derived implementations and versions, so treat the Paper values below as Paper defaults rather than universal settings.
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bukkit.yml is a YAML configuration file used by Bukkit-derived Minecraft Java servers, including Paper-based servers. It contains server-wide Bukkit settings and, on Paper, includes settings such as mob spawn limits and chunk garbage-collection behavior. The file is plain text, but YAML is indentation-sensitive: a misplaced space, tab, colon, or quotation mark can prevent the server from starting.
Paper maintains a version-specific bukkit.yml reference. Use that reference for the Minecraft/Paper version actually running on your server. A setting documented for one release may be renamed, moved to another configuration file, or ignored by a different implementation.
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Before you edit: stop, back up, and identify the server
Stop the server cleanly
Stop the server from its hosting panel or console before opening bukkit.yml. Editing while the process is running can be unsafe because the server may still have configuration or world data open, and a later shutdown may overwrite your changes. XGamingServer’s configuration guide likewise instructs administrators to stop the server before editing and restart it afterward: How to configure your Minecraft server (bukkit.yml).
Wait until the console or panel reports that the process has fully stopped. Do not merely close a terminal window or kill a Java process unless the server is unresponsive; an abrupt termination can cause separate world-save problems.
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Copy the current file before changing it. Give the copy a meaningful name such as bukkit.yml.backup-2026-10-14, or download it to your computer through the hosting panel. A backup lets you restore a known-good configuration if the server fails to start or a change produces unwanted gameplay.
- Back up the original file, not only the lines you intend to edit.
- Keep the backup outside the editor’s temporary directory so it is not lost when the panel closes.
- If several administrators work on the server, record who changed which setting and why.
Confirm the software and version
Note whether the server runs Paper, Spigot, or another Bukkit-derived implementation and record its exact version. The documented defaults in this article are from Paper’s reference; they should not be assumed to be the defaults for every fork. If a key is absent from your file, check the documentation for your build before adding it.
Where to find bukkit.yml
Self-hosted server
For a server you run yourself, bukkit.yml is normally in the server’s root folder: the same directory that contains the server JAR and folders such as world, world_nether, or plugins. Do not look inside a world folder or the plugins folder. If you launch the server from a script, the root folder is usually the script’s working directory.
- Open the folder from which the server is launched.
- Confirm that
bukkit.ymlis present. If the file has not yet been generated, start the server once, let it finish creating its files, stop it cleanly, and then check again. - Open the file with a plain-text or code editor that preserves spaces and UTF-8 text.
Hosted control panel
Most game-hosting panels expose the server root through a Files, File Manager, or similarly named tab. XGamingServer’s instructions use the panel’s Files tab: stop the server, open bukkit.yml, edit it, save it, and start the server again. Panel labels vary, but the file should still be in the top-level server directory rather than in a world or plugin subdirectory.
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- Use the panel’s Stop control and wait for the stopped status.
- Open Files (or the panel’s equivalent).
- Select
bukkit.ymlin the server root. - Choose Edit, Open, or the equivalent editor action.
How to edit bukkit.yml step by step
- Stop the server. Wait for the process to finish shutting down.
- Back up
bukkit.yml. Download it or duplicate it in the panel. - Open the root-level file. Make sure it is named exactly
bukkit.yml, notbukkit.yml.txt. - Find the section you need. Use your editor’s search function for a key such as
spawn-limitsorchunk-gc. - Change only the required value. Preserve the existing hierarchy and indentation. YAML requires spaces; do not insert tabs.
- Save the file. If the panel offers a save confirmation, wait until it reports success before leaving the page.
- Start the server. Watch the console from the beginning of startup.
- Check the result. Look for YAML parsing errors, confirm that the server reaches its ready state, and test the behavior in-game.
Changes made while the server is stopped take effect when it starts again. If the server starts normally but the behavior does not change, verify that you edited the active server’s root directory and that the key is supported by your implementation and version.
YAML editing rules that prevent startup failures
Use spaces and preserve nesting
Indent child keys consistently. The following structure shows the hierarchy used by Paper’s reference for spawn limits:
spawn-limits:
monsters: 70
animals: 10
water-animals: 5
water-ambient: 20
water-underground-creature: 5
axolotls: 5
ambient: 15The two-space indentation is illustrative of the documented structure. The critical rule is consistency: a child key must remain nested under its parent, and tabs should not be used for indentation.
Keep values in the expected form
Numbers should remain numeric. Do not add comments inside a number, replace a colon with another punctuation mark, or put unrelated text on the same line. If you need a note for another administrator, use a YAML comment beginning with # on its own line, provided your server’s configuration parser accepts it.
Check for accidental extensions
Some desktop editors hide file extensions and save a text file as bukkit.yml.txt. Enable visible extensions or inspect the filename in the panel. The server will read the correctly named file in its root; a second file with a hidden extension will have no effect.
Paper spawn limits in bukkit.yml
Paper’s bukkit.yml reference lists these default spawn limits:
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| Key | Paper default | What it represents |
|---|---|---|
monsters |
70 | Maximum hostile-monster spawn limit around players |
animals |
10 | Maximum animal spawn limit around players |
water-animals |
5 | Water-animal spawn limit around players |
water-ambient |
20 | Water-ambient spawn limit around players |
water-underground-creature |
5 | Water-underground-creature spawn limit around players |
axolotls |
5 | Axolotl spawn limit around players |
ambient |
15 | Ambient-mob spawn limit around players |
These values and their current placement are documented by Paper at Paper’s bukkit.yml reference. Paper also notes that the limits can be overridden in the Paper world configuration, so a world-specific setting may take precedence over a value you change in the global file.
What the limits do—and do not do
CraftServe explains that these limits apply to mobs spawning around players. Mobs in areas far from players are not loaded and therefore are not counted in the same way. Mobs created by spawners or commands are not subject to these natural-spawn limits; they have separate behavior and limits. Read the detailed explanation in CraftServe’s bukkit.yml guide.
Consequently, lowering monsters will not automatically remove every mob from a grinder, command-generated mobs, or entities already present in a world. It changes the applicable natural-spawn cap, and the observed effect depends on player locations, loaded chunks, existing entities, and other server settings.
When changing spawn limits makes sense
Administrators sometimes lower spawn limits as a performance experiment when natural mob spawning contributes to server load. Community recommendations vary, and no single set of replacement values is authoritative. Start with a small, documented change, restart the server, and observe both gameplay and server performance before changing another category. If the result is worse, restore the backup or return to the previous value.
Lower limits can reduce the number of naturally spawned mobs but may also reduce the availability of hostile mobs, animals, fish, or ambient creatures that players expect. A mob farm that relies on natural spawning can produce less, while a spawner-based farm may be largely unaffected by this setting.
Understanding chunk-gc
The chunk-gc section is more version-sensitive than the spawn-limit section, and published descriptions do not agree completely about its wording. Paper’s documentation describes period-in-ticks as how long chunks loaded by plugins should last and lists a default of 600 ticks. Paper caps the minimum at 20 ticks (one second). See the current definition at Paper’s bukkit.yml reference.
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CraftServe describes the same setting as the interval between checks for unused chunks in memory and says that 0 disables chunk garbage collection: CraftServe’s bukkit.yml guide. XGamingServer advises that this setting generally should not need to be changed: its bukkit.yml configuration guide.
How to handle the conflicting descriptions
- Use the documentation for your exact Paper or Bukkit-derived version as the authority.
- Do not assume that a value copied from another server has the same meaning on your build.
- Keep the existing value unless you have identified a specific chunk-loading problem and can measure the result.
- Change one setting at a time and retain a backup so you can undo the experiment.
A generic structure may look like this when the key exists in your file:
chunk-gc:
period-in-ticks: 600Do not add the section solely because you saw it in an example. First confirm that your server version documents it and uses that key name.
Testing a configuration change without guessing
Use a controlled change
Write down the original value, the new value, the date, and the reason for the change. Change one related key rather than editing spawn limits and chunk collection at the same time. This makes it possible to identify which edit affected mob availability, chunk behavior, or startup.
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Restart and inspect the console
Start the server after saving and watch the complete startup log. A YAML syntax error, unknown key, or malformed value may be reported before the server reaches its ready state. If the process stops during startup, stop attempting repeated restarts and restore the backup while the server is offline.
Test the gameplay scenario
For spawn-limit changes, test in the area and conditions where the problem occurs. Remember that limits concern natural spawning around players, not every entity source. For chunk-gc changes, test the plugin or feature that loads chunks and observe whether its behavior changes after the documented period or check interval for your version.
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Keep or revert based on evidence
A change is useful only if it addresses the original problem without creating an unacceptable trade-off. If mob farms stop working, expected animals disappear, or plugin-loaded chunks behave unexpectedly, restore the previous value and investigate the version-specific documentation before trying another number.
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The server ignores my change
- Confirm that the server was stopped before editing and restarted afterward.
- Check that you edited the active server’s root-level
bukkit.yml, not a backup, staging directory, or another server instance. - Confirm the key spelling, capitalization, nesting, and indentation.
- Check whether a Paper world configuration overrides the global spawn limit.
- Verify that the setting exists in the documentation for your exact server version.
The server will not start after saving
Stop the process, restore the backup, and start again. If the backup works, compare the edited lines for tabs, missing colons, incorrect indentation, non-numeric values, or an accidentally added section. Use the startup log’s line number when available. Do not delete unrelated sections just to make the error disappear; that can create additional configuration problems.
The file keeps reverting
Make sure you are using the panel’s Save action and waiting for confirmation. Some panels provide separate editor and upload workflows; in that case, upload the edited file only after the server is stopped and verify its timestamp or contents in the panel. A startup script or management tool may also regenerate configuration, so check which process owns the server if your edits disappear after every restart.
Mobs still appear after lowering a limit
Natural-spawn caps do not govern mobs created by commands or spawners, and mobs far from players are not loaded and counted in the same way. Existing entities may also remain until they despawn or are otherwise removed. Confirm that you are testing natural spawning near a player before concluding that the setting failed.
Performance became worse
Restore the previous value first. Then test changes individually on a server state that can be compared fairly. Because recommended replacement numbers differ across community guides, there is no universal “lag-fix” value supported here. Treat any suggested number as a starting point, not a guarantee, and keep the value that works for your server’s player count, plugins, worlds, and gameplay style.
Editing from a command-line server
If you administer a self-hosted server over SSH or a terminal, the process is the same: stop the Minecraft process, change directory to the server root, make a copy of bukkit.yml, edit it with a text editor, save, and restart using your normal launch script. The important safeguards are independent of the editor: the process must be stopped, the file must be the active root-level file, and the YAML hierarchy must remain valid.
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When not to change bukkit.yml
- Do not change
chunk-gcmerely because a forum post lists a different number; first establish what the key means on your version. - Do not lower every spawn category at once when diagnosing lag; you will lose the ability to identify the cause and may alter normal gameplay unnecessarily.
- Do not use bukkit.yml to control spawner- or command-created mobs when the documentation says those entities are governed separately.
- Do not assume a global value wins over a Paper world-specific override.
- Do not edit while the server is running or skip a backup for a production world.
A safe repeatable workflow
- Identify the server implementation and exact version.
- Read the matching configuration reference and locate the documented key.
- Stop the server cleanly from the panel or console.
- Back up the complete root-level
bukkit.yml. - Edit only the required value, using spaces and the existing indentation.
- Save and verify the file contents.
- Start the server and watch the startup log for parsing or unknown-setting errors.
- Test the specific gameplay or performance issue that motivated the change.
- Keep a record of the result; restore the backup if the change is ineffective or harmful.
This workflow separates file-editing mistakes from gameplay effects and gives you a fast recovery path. For Paper defaults and version-specific behavior, consult Paper’s bukkit.yml reference before adding or changing a key.
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