Servers - Aternos

Aternos not working? Server status and 5 fixes (2026)

If your Aternos server hangs in the queue, crashes right after startup, or your players get "connection refused", the cause is usually one of two or three typical things: the global queue, the RAM limit, or an incompatible plugin or mod. This guide goes through the most common symptoms one by one. We start with what to check in the panel and end with the cases where the problem isn't you but the platform itself.

Server won't start (queue, stuck)

The first symptom every new Aternos user runs into: you click START, and the server either sits in the queue or switches to "Preparing" and then nothing happens. That's usually not an outage, it's just how free hosting on shared infrastructure works.

The queue: when and why

Aternos has a limited pool of virtual servers shared between millions of users. When you click START, your request goes into a global waiting queue. At peak times (evenings, 5:00-11:00 PM Central European Time, and the whole weekend) the queue grows to hundreds of thousands and you'll wait 5-15 minutes. At night (3:00-7:00 AM Central European Time) servers start in 10-30 seconds.

The queue counter drops unevenly: sometimes you jump a hundred places at once, sometimes you sit on one number for a minute. That's normal. You can't skip the queue with any trick, VPN or payment, because Aternos deliberately doesn't offer a "premium without a queue" option.

The queue hasn't moved in 10 minutes

If the counter is frozen, check:

Is your internet connection working? A drop of a few seconds can kick you out of the queue
Refresh the browser tab and press START again, because the panel sometimes disconnects
Check status.aternos.org, since the whole platform may be down
Try a different browser or turn off your ad blocker (AdBlock can break the panel's JavaScript)

"Preparing" forever

The "Preparing" status means the server got its resources but can't initialize. The most common causes:

A corrupted world file after an earlier crash. Aternos should regenerate it, but sometimes it doesn't
A game version that doesn't match the installed mods (covered below)
An overfull /logs folder: clear the old logs in the Files tab

If "Preparing" hangs for more than 5 minutes, click STOP and press START again. Two or three restarts in a row usually fix it.

Tip: If you're planning a session at a set time, start the server 10-15 minutes early. That way you and your friends aren't waiting in the queue alongside players from all over the world, and you arrive at a server that's already running. For more getting-started tips, see the guide Aternos: how to create a server step by step.

"Server crashed" / Out of memory: RAM limits

The second classic Aternos problem: the server starts, runs for a bit, then stops with Server crashed. You open the console and see java.lang.OutOfMemoryError. That means your server exceeded its allotted RAM.

Why Aternos has so little RAM

Aternos allocates memory dynamically depending on pool load and plan (the free plan is the only plan, but Aternos rotates servers between machines with different specs). In practice you'll get 2-4 GB. There's no way to raise it for free. Your only options are to use the server less intensively or to migrate to paid hosting with guaranteed RAM.

How to recognize a memory crash

In the Console tab, look for lines like:

java.lang.OutOfMemoryError: Java heap space
java.lang.OutOfMemoryError: GC overhead limit exceeded

If you see either of them, the problem is a lack of memory, not a plugin or code.

How to cut RAM use

view-distance=6 (or 4 for modpacks) - the quickest win, since chunks are 80% of server memory use
simulation-distance=3 - reduces the number of active entities and redstone ticks
Remove unneeded plugins/mods - each one holds data in memory even when it isn't being used
Clear unneeded entities - dropped items, minecarts hanging in midair, AFK farms you don't need
Turn off chunk pregeneration - the command /chunky pause, if you use the Chunky plugin
Delete large, unneeded worlds - each dimension (the Nether, the End) uses memory even when nobody goes there

Modpack crash at startup

Heavy modpacks (RLCraft, All the Mods 9, SevTech Ages) can need 6-8 GB of RAM just to start. If your Aternos server got only 4 GB, a crash during bootstrap is almost certain. Solutions:

Pick a lighter modpack (for example Better MC instead of ATM9)
Install the Lite/Light variant if the modpack offers one
Move to a cheap paid host that gives you 6 GB of RAM

Mods and plugins block startup

After you add a pack of plugins or a few mods, the server stops starting. This situation always has the same cause: a version conflict or a missing dependency.

How to track down the culprit

Open the Console tab and find the last server start
Look for lines starting with [ERROR], Exception, Caused by
The mod/plugin name in that line is your culprit
Disable it in the Plugins or Mods tab and restart the server
If the server started, the culprit is confirmed

The most common phrases in logs and what they mean:

UnsupportedClassVersionError - the plugin/mod needs a newer Java version than the server uses
NoClassDefFoundError - a dependency is missing (for example Vault for economy plugins, Fabric API for Fabric mods)
Duplicate plugin - you have two different plugins under the same name (for example an old and a new JAR file in /plugins)
Failed to load mod - the mod doesn't match the Forge/Fabric or Minecraft version

The bisection method (always works)

If you have 20 plugins and don't know which one is at fault, disable half of them and restart the server. If it starts, the culprit was in the disabled half. If not, it's in the half that's still running. Keep halving until one plugin is left. The same method works for mods.

Version mismatch

A mod pack for Minecraft 1.20.1 won't work on a 1.21.4 server. Check the version of every mod/plugin on CurseForge or Modrinth: the version has to match the server version EXACTLY. Detailed installation steps are in our guide Aternos: how to install mods and plugins.

Note: Before you add a pack of 10 mods, make sure each one is built for the same Minecraft version AND the same mod loader (Forge or Fabric). A Forge mod won't run on Fabric and vice versa.

Can't connect to the server (offline, IP)

The server shows as online in the panel, but players get errors when joining. This one has the most causes, but they can all be sorted out.

"Can't connect to server"

The most common cause: the server is off even though you think you started it. On Aternos the server shuts down after 5 minutes without a player, so if you left and came back an hour later, it's no longer running. Check the status in the panel. If it's offline, click START and wait in the queue.

"Connection refused"

The server is off or Aternos has an outage. Check status.aternos.org. If it shows a platform outage, wait, because there's nothing you can do. If the status is green but the server is offline in the panel, restart it.

"Connection timed out"

A player gets this error when they try to connect to the wrong address or port. Make sure they enter exactly what you see in the panel (for example yourname.aternos.me), without adding an extra port of their own. Aternos sometimes assigns a non-standard port. In that case the address in the panel looks like yourname.aternos.me:25566, and that :25566 suffix MUST be entered along with the address.

"Outdated client" / "Outdated server"

The client version doesn't match the server version. Check the server version in the Aternos panel (it's shown on the dashboard) and ask players to switch their launcher profile to exactly that version. If you don't want to force players to change, install the ViaVersion plugin (Paper only), which lets newer clients connect to an older server.

"You are not white-listed"

The whitelist is on and the player's name isn't on it. Add them with a console command: whitelist add PlayerName, then whitelist reload. Keep in mind that the name has to be exact: capitalization doesn't matter, but typos do.

"Failed to verify username"

The Minecraft client can't verify the account. The causes: the player doesn't have a paid Minecraft account, their session expired (have them restart the launcher), or the Minecraft authentication servers are having an outage.

How to report a problem to Aternos

If none of the tricks above worked, you're left with contacting support. Aternos is free, so support is slower than at paid hosts, and you shouldn't expect an answer within a quarter of an hour. But you will get one.

The help center at aternos.org/support

This is the first place to look. Aternos has an extensive knowledge base answering the most common problems, split into categories (Getting Started, Plugins, Modpacks, Troubleshooting). There's a good chance your problem is already described there.

The community forum

On aternos.org/forums there is a community of users that often replies faster than official support. Search existing threads before opening a new one, because someone may have already described your problem. When you open a topic, include:

The server name (the aternos.me URL)
The Minecraft version and server software (Paper, Forge, Fabric)
The list of installed plugins/mods
A console excerpt with the error (the last 30-50 lines)
What you've already tried

The Aternos Discord

The official Aternos Discord is discord.gg/aternos. It has a #help channel where moderators and experienced users answer in real time. Before you ask a question, read the pinned rules post, because without that your request will be ignored.

The contact form

For problems that need action on Aternos' side (a suspended account, a dispute about the terms, a suspected attack), use the form at aternos.org/contact. A reply can take a few days, since this isn't a problem that calls for hurry.

When support can't help

Some Aternos limits can't be worked around: the queue, the auto-shutdown after 5 minutes, no fixed IP. Support won't remove them for you, because they are the foundation of the platform's business model. If these limits block you, the only way forward is migrating to paid hosting. You can compare the options in our ranking of the best Minecraft hosts and in the guide to free and cheap hosting.

FAQ: common questions about Aternos problems

Does Aternos delete the server world after long inactivity?

Yes. Servers unused for 3 months are marked inactive, and after another 6 months they are deleted completely along with the world. If you want to keep the map longer, start the server and join it at least once a quarter. It's also good practice to download a ZIP copy of the world from the Files tab: even if the account expires, the local copy stays.

Are there AFK limits on Aternos?

Aternos shuts the server down after 5 minutes with no players online. A player who is AFK (not moving) doesn't affect that counter: as long as their connection is active, the server keeps running. The problem can be anti-AFK plugins that disconnect idle players; when they disconnect the last person, the server shuts down after 5 minutes. If you want to AFK-farm, turn those plugins off or move to paid hosting.

Why does an Aternos server take so long to start?

Three layers of delay add up to a long start. The first is the global queue of waiting servers: 5-15 minutes at peak hours. The second is resource allocation and downloading your server files from Aternos storage (30-60 seconds). The third is Minecraft's own initialization, which can take 2-4 minutes with heavy modpacks. In total, from clicking START to online, it's typically 3-20 minutes depending on the time of day.

Can I recover a world after a crash that corrupted a file?

Aternos keeps a limited backup history in the Backups tab (if the plan supports it at the time; it's sometimes disabled for free accounts). Check there first. If it isn't there, try downloading the world folder through the Files tab and opening it with tools like MCA Selector or NBTExplorer: often only a single chunk is corrupted and you can cut it out without losing the rest of the map. Your own regular backups (a weekly ZIP) are the cheapest insurance.

Why does an Aternos server crash so often?

The most common causes are exceeding RAM (Out of memory), too many entities or chunks loaded at once, and conflicts between plugins/mods. Open the console after every crash: the first ERROR line usually says what failed. If the crash keeps happening even after you remove all add-ons, you're stuck with the Aternos RAM limit. Then your only way out is cutting view-distance to 4 or migrating to paid hosting with guaranteed RAM.