Fix a Minecraft server that will not start
Read the Console for the first real error, match the message to a fix, and undo your last change in the safe order, from add-ons to backups.
When a server will not start, the Console is the first place to look. Find the first real error, not the lines after it. This guide shows where to look, lists the messages we see most with what they mean, and gives the safe order for undoing a change that broke the server.
Checked against Minecraft 26.3's own server files and the OpenJDK 25 launcher, October 2026.
Read the Console first
- Open the Console tab and click Start.
- Scroll to the first error after the start. Start with that line, not the ones after it.
- To save the recent log, click Download Log and choose Last hour, or Earlier boots (7 days) for a start before the last restart.
A healthy start ends with a line like Done (4.2s)! For help, type "help". The panel counts the server as started when it sees )! For help, type in the log. Before that, a line reading Preparing level means the world is loading.
Match the message to the fix
If the last line is only Failed to start the minecraft server, the real cause is a few lines above it. Find Minecraft server logs and crash reports and Minecraft server exit codes 1, 137 and 143 help with the rest.
Out of memory
Your plan's RAM is fixed, and the panel sets the Java heap from it at every start, so you cannot raise it by editing a flag. Take load off instead: remove the newest add-ons, lower View distance (chunks) and Simulation distance (chunks) under Performance in Config Editor, or choose a larger plan with Change plan in Settings. How much RAM does my Minecraft server need? gives sizes.
Undo your last change
Start by undoing the last thing you changed, in this order:
- A new plugin or mod: open Plugins or Mods, click Installed and Disable it, then Start the server.
- A software or version change: open the JAR Manager. If a Previous jar kept. card is there, stop the server and click Restore previous jar.
- Anything else: open Backups and restore the last backup that worked.
Restoring a backup overwrites the current server files with the ones in the backup, and the panel says this cannot be undone. It stops the server first and starts it again afterwards. Take a new backup first if the server can run at all.
Last resort
Reinstall under Danger zone in Settings runs the installer again. The panel warns that files may be overwritten or removed, so make a backup first. Use it only when the steps above did not work.
If the server still will not start, send support the downloaded log through Contact support and open a ticket.
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