Fix: Error 198 on Aternos Minecraft

Finding that modded world only to be hit with an error right as you try to get your server running is definitely a headache!

On Aternos, Error 198 is a timeout or WebSocket connection error that happens specifically when a world upload fails to complete. Essentially, your browser is taking too long to send the world data to the Aternos servers, so the connection simply drops. Because modded worlds tend to generate huge file sizes and contain a lot of complex data, this is a very common hurdle when moving them to a host.

Here are the most effective ways to bypass Error 198 and get your world uploaded:

1. Use the “Legacy Upload” Method (Most Effective)

Aternos has a hidden alternative upload system that bypasses the standard, sometimes-buggy WebSocket method.

• Go to the Worlds page on your Aternos dashboard.
• Hold down the Ctrl key on your keyboard, and while holding it, click the Upload button.
• Select your .zip file.
• Note: This method is much more reliable for unstable connections, but it does enforce a strict file size limit of 200MB.

2. Double-Check the Compression Format

Aternos will only accept your world if it is zipped correctly. If it is trying to process an uncompressed folder or a .rar file, it will struggle to read it, eventually time out, and throw Error 198.

• Right-click your world folder (the one containing level.dat) and select Send to > Compressed (zipped) folder. Ensure the final file ends exactly in .zip.

3. Change Browsers and Disable Ad-Blockers

Sometimes, the timeout is forced by your browser’s security protocols or an overactive extension aggressively blocking the upload script.

• Try uploading the world using a completely different browser (like Edge, Chrome, or Firefox).
• Temporarily turn off any ad-blockers, pop-up blockers, or strict firewall settings while the upload is running.
• Avoid doing heavy internet tasks on your network (like watching videos or downloading files) while the upload is in progress to ensure your bandwidth is fully dedicated to Aternos.

4. Trim the World Size

If your modded world is simply too massive (especially if it is over that 200MB legacy limit), your internet connection might not be able to push it through fast enough before the Aternos servers cut the connection.

Trimming your world size with MCASelector is a fantastic way to get past those strict Aternos upload limits. It can feel a little intimidating to delete parts of your world, but because the tool is completely visual, you can see exactly what you are keeping and what you are wiping away.

Here is a straightforward guide to shrinking your world size safely.

1. Make a Complete Backup First

Before opening any third-party editing tool, make a complete copy of your world folder. If you accidentally delete your main base, you will want that backup to restore everything. Just copy and paste your world folder onto your desktop for now.

2. Download and Open MCASelector

MCASelector is a free, open-source tool. You will need to have Java installed on your computer to run it, which you likely already have if you are playing modded Minecraft.

• Download the latest release from the official MCASelector GitHub page.
• Run the downloaded .jar or .exe file to open the application.

3. Load Your Minecraft World

Once the program is open, you need to point it to your specific world file.

• Click File in the top left corner, then select Open World.
• Navigate to your .minecraft\saves folder (or your specific modpack’s save folder) and select the world you want to shrink.
• The tool will load a top-down, 2D map of your entire generated world. Every rendered block you see represents data taking up file space.

4. Select the Unwanted Chunks

You can manually click and drag to select areas, but the smartest way to shrink a world is by using the tool’s built-in filters to find chunks you simply walked past and never actually built in.

• Click Tools at the top, then select Filter chunks.
• Set the filter condition to target InhabitedTime. Set the value to something low, like < 5 minutes. This targets areas where players have spent almost no time.
• Click Select. The map will automatically highlight all those untouched chunks in orange.

5. Delete and Shrink

Now that the unused data is highlighted, you can wipe it out. Don’t worry about breaking your game—if you ever walk back to those exact areas in the game, Minecraft will just freshly generate them again from scratch!

• Click Selection at the top, then choose Delete selected chunks.
• A warning will pop up. Confirm the deletion.
• Close the program. MCASelector saves the changes automatically directly to your world folder.

Right-click your newly trimmed world folder and check its properties. The file size should be significantly smaller and ready to easily slide past that Aternos Error 198!

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Zip Files Correctly

Getting the zip format right is the final hurdle. Aternos is notoriously picky about how world files are packaged. If the folder structure inside the zip is nested too deeply, the server won’t be able to find the level.dat file to boot up the world.

Here is the most foolproof way to compress your trimmed world so Aternos accepts it immediately.

1. Verify the Folder Structure

Before zipping anything, you need to make sure you are compressing the correct folder.

• Open your saves folder and find your newly trimmed world folder.
• Open that specific world folder.
• Look inside and verify you immediately see files like level.dat, session.lock, and the region folder.
• If you see these files, step back out to the main saves folder. You are ready to compress it.

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2. Compress the Folder

Do not use third-party tools to make a .rar or .7z file. Aternos only accepts standard .zip files.

• On Windows 10: Right-click the world folder, hover over Send to, and click Compressed (zipped) folder.
• On Windows 11: Right-click the world folder and select Compress to ZIP file.
• Windows will generate a new file with a zipper icon next to your original folder.
• Rename this new zip file to something simple with no spaces or special characters (for example, ServerWorld.zip).

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3. Upload to Aternos

Now that you have a clean, standard zip file, it is time to upload it to your server.

• Log into your Aternos dashboard and navigate to the Worlds tab on the left menu.
• Click the Upload button (remember to hold down the Ctrl key while clicking if you want to use that stable legacy upload method we discussed earlier).
• Select Zip archive from the dropdown menu if prompted.
• Locate and select the ServerWorld.zip file you just created.
• Wait for the progress bar to finish. Do not close the tab until the page refreshes and shows your uploaded world.

Also Read: Issues With Minecraft TLauncher Worlds? Try These 4 Fixes