Things may not go as expected and your server may suddenly crash unexpectedly. To help you locate the issue, make sure to read through this guide. If you are still stuck then don't hesitate to open a ticket where one of our Support Team members will assist you.
Crash: World Issues
Your world can cause your server to crash for a number of reasons. Below will be examples of crashes caused by worlds and an explanation of the issue;
Example 1 - Wrong Version: https://pastebin.com/qusjCbUW
If you generate or update a world to a newer version and then changing back to an older version. Older Minecraft servers cannot understand the newer worlds, and so they cannot start.
These kinds of errors usually include one of the following at the top of the error:
net.minecraft.server.<version>.NBTTagCompound.a
net.minecraft.server.<version>.NBTTagCompound.load
Fixing the world being the wrong version:
Delete your worlds and restart your server; or
Switch back to the newer version the world was made or upgraded on; or
Switch back to the newer version the world was made or upgraded on, use WorldEdit to save your buildings as a schematic, delete the world and switch back to the old version, paste in the structures. [Only works if the structures have no new blocks.]
Example 2 - Corrupted Chunk: https://pastebin.com/hsdfAexL
Sometimes, world chunks can become corrupted and cause your server to crash. These crashes are usually obvious, containing one of the following lines:
net.minecraft.server.<version>.ChunkSection.a
net.minecraft.server.<version>.Chunk.a
Fixing a corrupted chunk:
Delete your worlds and restart your server; or
Use RegionFixer on your world, located here. Note that Mac users need Python 2.7, Windows users can use the Windows executable file.
Example 3 - Session lock: https://pastebin.com/7BZu9Na8
Sometimes the server may not be able to access the session.lock file in your world. This can cause many issues, so the server will crash to prevent issues. There is only one fix for this, which is to access your server files, open the "world" folder, and delete the session.lock file
Crash: Other
Example 1 - YAML Crashes: https://pastebin.com/0iJneEEa
Sometimes, your server may crash due to errors in a YML file. This is unlikely to be a plugin-side issue, those usually just throw errors, however it's not impossible. This is likely from BungeeCord's config.yml, Bukkit's bukkit.yml, Spigot's spigot.yml, etc. Make sure to read through both of the sections below so you can find the exact cause.
Most of the time, YAML crashes are not due to plugins. Usually, these will say the file it is located in right at the top as the server tries to load them in:
[Server] ERROR Could not load spigot.yml, please correct your syntax errors
The error will tell you where the issue is. We recommend using https://yamllint.com just to make sure as it pinpoints exactly where the issue is and tells you what is causing it.
If you have tried to fix your YAML file(s) and are still having issues with it, feel free to open a ticket and we'll help you.
Example 2 - Plugin Crashes: https://pastebin.com/mMk58Mg0
This is the most common type of crash. This is where a plugin causes your server to crash.
When reading these crash reports, always look between the two sections that say "_Server thread dump_" and "_Entire Thread Dump_" and try to find any plugins mentioned in there. In the example above, we can see "_com.earth2me.essentials.spawn_" which tells us this crash is from Essentials Spawn. From here, you can contact the author of the plugin.
