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Exception in thread "main"
COAL-004 · Unhandled exception during startup
The server threw an unhandled exception while starting. Why this line is a symptom rather than a cause, and where in the log the real reason is.
What it looks like in the logException in thread "main" java.lang.RuntimeException: Failed to start the minecraft server at net.minecraft.server.Main.main(Main.java:265)
What it means
Something failed during startup and nothing caught it, so Java printed the stack trace and quit. On its own this line tells you almost nothing - it is the outermost wrapper around whatever actually went wrong. The real cause is either further down the trace, after a Caused by: line, or in the log lines immediately above it.
How to fix it
- Read up, not down. Scroll to the last few lines before this one. Mod loaders print their real complaint - a missing dependency, a version mismatch - just before the exception escapes.
- Follow every
Caused by:to the end of the chain. The last one is usually the actual fault. - Check the common specific causes that arrive wrapped in this: a missing dependency, a client-only mod, or an unaccepted EULA.
Coalstack's Auto Debugger exists largely for this case - it scans the whole log and reports the specific finding instead of the wrapper.