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Server will not start: the first five checks

Ninety percent of "it won't start" tickets end at one of these five. Do them in order.

1 min readUpdated 2026-09-14Diese Anleitung auf Deutsch lesen →
  1. Read the last 30 lines of the console. The reason is almost always written there. Words to look for: Exception, Error, Could not, Failed, OutOfMemory, EULA, port.
  2. EULA (Minecraft). You need to agree to the EULA → accept it in the pop-up or set eula=true in eula.txt.
  3. Memory. The resource bar hits 100 % and the process dies without a Java error, or the log says OutOfMemoryError → Out of memory.
  4. A plugin or mod. Could not load plugin, Mixin apply failed, Missing dependency, Incompatible mods → the log names it. Move the file out of plugins/ or mods/, start again. Install a version that matches your Minecraft version.
  5. A broken config or world. while parsing a block mapping (YAML), Failed to load level.dat, Exception reading region file → Editing configs or Corrupt world.

Still nothing?

  • Startup variables sane? A Minecraft version that does not exist (1.21.99) makes the install fail silently. Settings → Reinstall after fixing it.
  • Disk full? Nothing can be written → Disk quota.
  • Ask Kowalski: "read the log and tell me why the server stops". It does steps 1-5 in seconds.
  • Then a ticket with the console output.