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Incomplete Startup

The server begins starting but stops before it is fully up, with no clear single crash. Something during initialization, a config, a plugin/mod, or the environment, prevents it from finishing.

What does this error mean?
'Server failed to start' is a general startup failure: the process initialized partway then aborted. The real cause is in the log above the message, a failed plugin/mod, a bad config value, or a missing requirement. 
Server failed to start
Most Common Causes
  • A plugin/mod erroring during load.
  • An invalid value in server.properties or a config.
  • A missing dependency or file.
  • Insufficient memory to initialize.
  • A failed EULA acceptance or missing world files.
How To Diagnose
  1. Read the full log from the top, the first error is the key.
  2. Check that eula.txt is accepted.
  3. Validate server.properties and recently changed configs.
  4. Try a clean start with no plugins/mods to isolate.
Recommended Fixes
  • Fix the first error
    Resolve the earliest error in the log, later messages are often consequences of it.
  • Accept the EULA
    Set eula=true in eula.txt if the server stopped at the EULA check.
  • Repair the config
    Correct or regenerate the config/property causing the failure.
  • Bisect plugins/mods
    Remove them all, confirm it starts, then add back in halves to find the culprit.
Analyze My Log
Frequently Asked Questions

The top of the log. The earliest error usually explains the whole failed startup.

Yes, a fresh server will not start until eula=true is set in eula.txt.

Start with no plugins/mods and a default config, then reintroduce changes until it breaks.