This relates to MC-38134, MC-38515, and MC-32850. However, I wish to report a different aspect of the general issue. Which is that no crash report is being generated for this crash during saving the world. Nor does it appear in latest.log. Essentially, if your not watching it, or not able to watch it, it will never be seen.
While the errors themselves are their own bugs, that critical errors can occur without a crash report being generated is its own bug.
I first noticed this with the following random error that appears when saving the world:
ERROR Attempted to append to non-started appender ServerGuiConsole
Exception in thread "Server Shutdown Thread" org.apache.logging.log4j.core.appender.AppenderLoggingException: Attempted to append to non-started appender ServerGuiConsole
at org.apache.logging.log4j.core.config.AppenderControl.callAppender(AppenderControl.java:89)
at org.apache.logging.log4j.core.config.LoggerConfig.callAppenders(LoggerConfig.java:425)
at org.apache.logging.log4j.core.config.LoggerConfig.log(LoggerConfig.java:406)
at org.apache.logging.log4j.core.config.LoggerConfig.log(LoggerConfig.java:367)
at org.apache.logging.log4j.core.Logger.log(Logger.java:110)
at org.apache.logging.log4j.spi.AbstractLogger.info(AbstractLogger.java:1011)
at net.minecraft.server.MinecraftServer.s(SourceFile:379)
at net.minecraft.server.MinecraftServer$2.run(SourceFile:713)
Linked issues
Comments
Sorry, for whatever reason that one didn't come up in my searches.
Actually, no that one is still about the errors themselves and not the fact they aren't generating reports or otherwise being logged.
Edit: Due to the nature of the errors I can understand why they aren't being logged, however, when such an error occurs I expect a crash report generated. Which is to say that there are critical error conditions under which crash reports are not being generated is a bug unto itself.

This site is for bug reports only; feature suggestions are not accepted.
Now I'm scratching my head. How is reporting a failure in the crash report system a feature suggestion?
I'm still trying to figure how to respond to this without being facetious. That this could be taken as a feature request would mean that the Crash Reporter was not designed or implemented with the intent of catching and reporting crashes.

Apologies for not explaining. My understanding is that this ticket is saying that the game is not filing a crash report. Did the game crash and fail to file a crash report?
Exactly, the server is crashing as it saves the world yet no report is generated. If it crashes with the error I noted after "Saving players" it never gets to "Saving worlds" because its dead. Any changes that hadn't been saved to disk are lost because its dead. It crashed, but, no report was generated.
Edit: I apologize if my wording is getting funny. I've a medical condition that is starting to take effect.

Apologies, I mis-interpreted the ticket.

Is this still an issue in the current Minecraft Snapshot 15w47c or later? If so, please update the affected versions in order to best aid Mojang ensuring bugs are still valid in the latest releases/pre-releases.
The frequent world corruption this issue was hiding caused me to quit playing for a long time. Whenever I get back to Minecraft it will be the first thing I check.
Affects 15w49b. Still no minecraft for me.

Is there a way to reproduce such an exception?
This particular bug could maybe be fixed by using a newer version of log4j. The latest version is currently version 2.5, however Minecraft is using version 2.0-beta9 (Windows: %appdata%\.minecraft\libraries\org\apache\logging\log4j\log4j-core
). Additionally there is a similar looking bug that affects version 2.0-beta9 but is fixed in version 2.1: LOG4J2-392.
Write an automation script in your favorite language that repeatedly launches and shuts down the server. You will eventually see it along with MC-38134.
Is this still an issue in 1.9.3-pre2?
Dupe of MC-38134