Updated 1 November 2026
Your Minecraft server stopped by itself or won't start at all? The server almost always tells you why. This guide shows where to look, and how to fix the six most common causes.
1. Find the error
In SparkPanel, open the Console and start the server. Read the last red lines before it stops. Need more? Open Files:
logs/latest.log: everything from the last start.crash-reports/: a report for every real crash, newest at the bottom. The line underDescription:and the first lines after it tell you what went wrong.
2. The six most common causes
Wrong Java version
Error: UnsupportedClassVersionError or "has been compiled by a more recent version of the Java Runtime". Every Minecraft version needs its own Java version:
| Minecraft | Java |
|---|---|
| 26.x | 25 |
| 1.20.5 to 1.21.x | 21 |
| 1.18 to 1.20.4 | 17 |
| 1.16 and older | 8 or 11 |
Change it under Settings → Version (Java / runtime) in SparkPanel and restart.
Out of memory
Error: java.lang.OutOfMemoryError, or the server stops without an error while the memory graph is at the top. Remove heavy mods, lower the view distance (see Fix Minecraft server lag), or upgrade your plan. How much RAM do you need?
A client-only mod on the server
Error mentions net/minecraft/client, or Fabric says a mod is for environment client. Mods like minimaps, shaders and zoom mods only belong on players' computers. Remove them from the server's mods folder.
A missing or wrong mod version
Error: "requires" another mod, "Missing or unsupported mandatory dependencies" or "Incompatible mods found". Install the mod it names, in the version it asks for, or remove the mod that needs it. Every mod must match your Minecraft version and loader (Fabric, Forge or NeoForge).
A plugin for another version
Error in a plugin's name while the server keeps running, or the server stops right after "Enabling ...". Update that plugin to a version for your Minecraft version, or remove it from plugins.
A broken world
Error mentions a chunk, region or "Exception ticking world". This sometimes happens after a crash during saving. Restore the last good backup under Backups in SparkPanel. We make one every night.
3. Still stuck?
Remove mods or plugins you added recently, one at a time, and start after each. When the server starts, you found the cause. Or email info@serverspark.nl with your server name and the crash report: we'll take a look.