Minecraft Server Crashing on Startup? How to Fix It (2026)

When a Minecraft server crashes on startup, the answer is almost always written in logs/latest.log or the newest file in crash-reports/. The usual causes, in order of how often we see them: the wrong Java version, a mod or plugin that does not match the server, a client only mod on the server, not enough RAM, the EULA not accepted, the port already in use, or a corrupted world. Read the log first, match the error to the table below, and fix that one thing.

Step 1: Find the error in the log

Two places to look, both in the server's root folder:

• logs/latest.log: everything the server printed on its last run. Every crash shows up here, including ones that never create a crash report.
• crash-reports/crash-<date>-server.txt: written when the game itself crashes. The newest file is the one you want.

How to read them without getting lost:

1. Scroll to the end of latest.log and work upwards. The last ERROR or Exception before the server stopped is usually the cause. Earlier warnings are often harmless.
2. In a crash report, read the line after Description: and the first 5 to 10 lines of the stack trace below it. Look for a mod or plugin name in those lines.
3. On modded servers, the crash report ends with a list of loaded mods. Useful for spotting a mod that should not be there.

On GamezServers, the Console tab shows the live output as the server starts, and the Files tab opens logs/latest.log and the crash-reports folder in the browser.

Quick lookup: error message to fix

Fix 1: Java version mismatch

Each Minecraft version needs a minimum Java version. Start a 26.x server on Java 21 and it dies instantly with something like:

java.lang.UnsupportedClassVersionError: net/minecraft/bundler/Main has been compiled by a more recent version of the Java Runtime (class file version 69.0), this version of the Java Runtime only recognizes class file versions up to 65.0

The class file number tells you what Java it wants:

The reverse also happens. Old modded servers, especially Forge 1.16.5 and older, can crash on a Java that is too new, often with errors about modules, reflection or ClassCastException early in loading.

Self hosting: install the right Java (Eclipse Temurin is a good free build) and point your start script at it. On GamezServers, new Minecraft servers run on Java 25, which covers current versions. If you run an older version that needs an older Java, email support@gamezservers.com with the Minecraft version and we will switch your server's Java.

Fix 2: EULA not accepted

On a fresh self hosted server, the first start creates eula.txt and stops with:

You need to agree to the EULA in order to run the server. Go to eula.txt for more info.

Open eula.txt, read the linked Minecraft EULA, change eula=false to eula=true, save and start again. On GamezServers this is done for you when the server is created.

Fix 3: Port already in use

**** FAILED TO BIND TO PORT!
The exception was: java.net.BindException: Address already in use
Perhaps a server is already running on that port?

Self hosting, it means another program is using the port, usually a second copy of the server you forgot was running. Close it (check Task Manager for java.exe or javaw.exe) or change server-port. It also happens when server-ip in server.properties is set to an address the machine does not have. Leave server-ip blank.

On a hosted server, this almost always means server-port or server-ip was edited. Put server-port back to the port in your server address and clear server-ip. If you are not sure what the port was, it is the number after the colon in the address at the top of the GamezServers panel. Geyser can cause the same error if it is set to a port something else uses: see our Geyser guide.

Fix 4: Out of memory

java.lang.OutOfMemoryError: Java heap space

The server ran out of the RAM it was given. On a vanilla or Paper server this is rare and usually means a giant farm or a plugin leaking memory. On a modpack it usually means the plan is too small for the pack. Big packs need 8 GB or more just to start comfortably. See how much RAM a Minecraft server needs. On GamezServers you upgrade from Settings, prorated, and restart.

Fix 5: Mod problems (Fabric, Forge, NeoForge)

Most modded startup crashes are one of these:

• Client only mod on the server. Forge and NeoForge say Attempted to load class net/minecraft/client/... for invalid dist DEDICATED_SERVER. Minimaps, shaders, menu mods, zoom mods and sound mods are the usual suspects. Remove the mod named in the crash.
• Missing dependency. Missing or unsupported mandatory dependencies (NeoForge and Forge) or an incompatible mod set error (Fabric) lists the mod that is needed. Install it, or the right version of it. On Fabric, Fabric API is the one people forget.
• Wrong Minecraft or loader version. A mod for 1.20.1 does not load on 1.21.1. A Forge mod does not load on Fabric. A NeoForge mod for 1.21 does not load on Forge. Check the version on the mod's download page.
• Two mods that conflict. The crash names one or both. Remove one, or check each mod's page for a known incompatibility.

If the log does not name a culprit, bisect: move half the mods out of mods, start, and repeat with the half that crashes. It sounds slow but finds the bad mod in a handful of restarts even with a hundred mods. Click Backup before you start pulling mods out. Our guide to running a CurseForge modpack server covers pack specific issues.

Fix 6: Plugin problems (Paper, Purpur)

A broken plugin rarely stops Paper from starting. The plugin fails, the console shows Error occurred while enabling <Plugin>, and the server carries on without it. If the server does stop, the plugin named just before the error is the suspect. Move its .jar out of plugins, start again, and get the build that matches your Minecraft version. Plugins built for a newer Java show the same UnsupportedClassVersionError as above, with the plugin's name in it. More in how to install plugins.

Fix 7: Corrupted world

Signs: errors mentioning level.dat, Exception reading a region file (r.0.0.mca and similar), or a crash every time the server loads a certain area. Usually caused by the server being killed mid save, a disk filling up, or files uploaded while the server was running.

What to try, in order:

1. Restore a backup. The cleanest fix. On GamezServers, pick a backup from before the problem and restore it.
2. Use level.dat_old. If only level.dat is damaged, stop the server, rename level.dat to level.dat_broken and level.dat_old to level.dat, then start.
3. Remove the bad region file. If the log names one region file, moving it out regenerates that 32 by 32 chunk area as new terrain. You lose any builds there, so only do this for an area nobody cares about.

Since 26.1, the world folder layout changed: the overworld's region files moved to world/dimensions/minecraft/overworld/region, and the Nether and End moved under world/dimensions/minecraft/ too. Older guides that tell you to look in world/region or DIM-1 refer to the pre 26.1 layout.

Always stop the server before uploading or replacing world files, so it does not overwrite your changes while saving.

Fix 8: Version downgrade

A world saved in a newer Minecraft version cannot be loaded by an older one. If you changed the server back to an older version, or uploaded a world from a newer singleplayer game, the server refuses to load it or crashes. Set the server to the version the world was last played on (or newer). Downgrading a world is not supported by Mojang. Restore the backup from before the version change instead. If players see "Outdated server" or "Outdated client" rather than a crash, read how to fix outdated server and client.

Fix 9: A typo in a config file

A broken server.properties usually just falls back to defaults, but broken plugin and mod configs (YAML, TOML, JSON) can stop them loading. YAML files hate tabs and missing spaces after colons. If a crash started right after you edited a config, undo that edit first.

When the server stops with no error at all

If the log just ends, with no exception, the process was killed from outside. On a home PC that is often the operating system closing it for using too much memory. On a hosted server it can mean the server hit its memory limit including Java's own overhead. Check memory use in the panel. If it was near the limit, upgrade or trim mods.

FAQ

Where is the Minecraft server crash log?

In the server's root folder: logs/latest.log for the last run and crash-reports/ for full crash reports. Older logs are zipped in logs/ by date.

Why does my server crash after "Preparing spawn area"?

Usually a mod or datapack crashing during world generation, or not enough RAM to generate the spawn on a heavy pack. Read the error just after that line in latest.log.

Can a plugin crash a Paper server on startup?

Rarely. Paper usually disables the broken plugin and carries on. If it does crash, the plugin is named near the bottom of the log. Remove it and start again.

My server says Done, then crashes when someone joins. Is that a startup crash?

Not quite. That is usually a mod mismatch between the player and the server, or a crash in the area the player logs in to. Check the crash report from that moment for the mod or chunk named.

Should I delete the world to fix a crash?

Almost never. Most crashes are Java, mods or config. Take a backup first, fix the cause, and only touch the world if the error points at world files.

Still stuck?

If you are on a GamezServers Minecraft server, send the newest crash report or latest.log to support@gamezservers.com, any time of day, and we will tell you what it says. Every server has 3 one click backups, so test fixes freely. If startup is fine but the server lags once people join, the lag fix guide is the next stop.