> ## Documentation Index
> Fetch the complete documentation index at: https://docs.purpify.host/llms.txt
> Use this file to discover all available pages before exploring further.

# Remove client-only mods from a server

> Identify a Minecraft Java server crash caused by a client-only mod and remove the incompatible file safely.

A client-only mod uses rendering, menus, input, or other code that is unavailable on a dedicated server. If one is uploaded to `/mods`, the server may stop during startup.

## Identify the incompatible mod

1. Start the server once and read the first relevant error in the [console](/panel/console).
2. Look for a mod name near messages such as `requires environment type CLIENT`, `invalid dist DEDICATED_SERVER`, `NoClassDefFoundError`, or `ClassNotFoundException`.
3. Compare the named file or mod ID with the files in `/mods`.
4. Check the mod author's page to confirm whether it is client-only or has a separate server-compatible release.

<Warning>
  A class-loading error can also be caused by a missing dependency or incompatible version. Do not remove unrelated mods merely because their names appear later in the stack trace.
</Warning>

## Remove and test

<Steps>
  <Step title="Stop the server">
    Leave it stopped while changing mod files.
  </Step>

  <Step title="Keep a copy">
    Download the suspected `.jar` or move it outside `/mods` so you can restore it if the diagnosis is wrong.
  </Step>

  <Step title="Start once">
    Start the server and watch the full startup. If it fails again, diagnose the new first relevant error rather than removing several files at once.
  </Step>

  <Step title="Check player clients">
    Keep client-only mods on player devices when desired. Server-required mods and dependencies must remain compatible on both sides when the mod author requires them.
  </Step>
</Steps>

For other startup failures, follow [Troubleshoot a server that will not start](/troubleshooting/server-wont-start).