# How to Fix "Failed to Check Session Lock" on a Minecraft Server

> This error means two copies of the world tried to open at once, or the lock file is stuck. Here's how to clear it on Beacon.

Source: https://www.beaconhosting.org/knowledgebase/failed-to-check-session-lock
Category: Minecraft
Last updated: 2026-10-22

`Failed to check session lock, aborting` appears when Minecraft can't take the lock on your world folder. Each world has a small file called `session.lock`; the server holds it while the world is open so nothing else changes it at the same time.

## Why it happens

- **The server was started twice**, or an old process hadn't finished shutting down when a new one started.
- **The server crashed** and left the lock behind.
- **The world was edited while the server was running**, for example by uploading a world over SFTP or running a map editor on it.

## How to fix it

1. Open your server and go to **Console**.
2. Click **Stop**. If it hasn't stopped after a minute, use **Kill**.
3. Wait until the status shows the server is offline.
4. Go to **Files** and open your world folder (usually `world`).
5. Delete `session.lock`. Minecraft makes a new one on the next start, so this is safe.
6. Go back to **Console** and click **Start**.

> [!WARNING]
> Never edit or replace world files while the server is running. Stop it first, make your change, then start it again.

## If it keeps happening

- Check that only one process uses the world. A plugin or mod that copies or backs up worlds while the server runs can cause it.
- Look at the full log in `logs/latest.log` (in **Files**) for the first error, not just the last one.
- Restore a recent backup from **Backups** if the world won't load at all.

Still stuck? [Open a ticket](/billing/tickets) and include your `latest.log`.