How to Read the Crash Report and Find the Culprit Mod

Understanding what the mod prints

When the Unsafe World Random Access Detector catches an off-thread world random access, it does not silently fix anything. Instead it logs a stack trace pointing at the exact code that touched the world's random source from the wrong thread. Your job is to read that trace, not the vanilla crash screen.

Steps

1. Reproduce the crash or the warning, then close the game fully so the log file is flushed.

2. Open your instance's logs/latest.log (or the crash report in crash-reports/) in a text editor.

3. Search for the phrase LegacyRandomSource or multiple threads. The detector's message usually appears just above the vanilla error.

4. Read the stack trace from top to bottom. The top frames are the offending call site; the frames below show which mod or vanilla class invoked it.

5. Look for package names that match a mod's ID (for example, a chunk-loading or worldgen mod). That package is your prime suspect.

6. Cross-check by disabling that single mod and repeating the same action that triggered the crash.

What to do with the result

The detector only identifies the cause. Report the stack trace to the suspect mod's issue tracker, or remove/replace the mod until it is fixed. If the trace points only at vanilla classes, a mod is still calling into them off-thread, so look one or two frames deeper for a mod package.