BootstrapMethodError - cannot find class definition

I have a Java webapp running on Jetty (version 9.4.20).
It uses a custom library for accessing MySql database, which has always worked well.

At random, sometimes, this exception is thrown:

java.lang.BootstrapMethodError: java.lang.NoClassDefFoundError: java/lang/IndyBootstrapDispatcher
        at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:222)
        at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:844)
        at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1604)
        at org.eclipse.jetty.websocket.server.WebSocketUpgradeFilter.doFilter(WebSocketUpgradeFilter.java:226)
        at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1591)
        at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:542)
        at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:143)
        at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:536)
        at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:127)
        at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:235)
        at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:1581)
        at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:233)
        at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1307)
        at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:188)
        at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:482)
        at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:1549)
        at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:186)
        at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1204)
        at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:141)
        at org.eclipse.jetty.server.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:221)
        at org.eclipse.jetty.server.handler.HandlerCollection.handle(HandlerCollection.java:146)
        at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:127)
        at org.eclipse.jetty.server.Server.handle(Server.java:494)
        at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:374)
        at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:268)
        at org.eclipse.jetty.io.AbstractConnection$ReadCallback.succeeded(AbstractConnection.java:311)
        at org.eclipse.jetty.io.FillInterest.fillable(FillInterest.java:103)
        at org.eclipse.jetty.io.ChannelEndPoint$2.run(ChannelEndPoint.java:117)
        at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.runTask(EatWhatYouKill.java:336)
        at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.doProduce(EatWhatYouKill.java:313)
        at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.tryProduce(EatWhatYouKill.java:171)
        at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.run(EatWhatYouKill.java:129)
        at org.eclipse.jetty.util.thread.ReservedThreadExecutor$ReservedThread.run(ReservedThreadExecutor.java:367)
        at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:782)
        at org.eclipse.jetty.util.thread.QueuedThreadPool$Runner.run(QueuedThreadPool.java:918)
        at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.NoClassDefFoundError: java/lang/IndyBootstrapDispatcher
        ... 36 more
java.lang.BootstrapMethodError: java.lang.NoClassDefFoundError: java/lang/IndyBootstrapDispatcher
        at com.mysql.jdbc.StatementImpl.executeQuery(StatementImpl.java:1421)
        at com.mchange.v2.c3p0.impl.DefaultConnectionTester.activeCheckConnection(DefaultConnectionTester.java:286)
        at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.testPooledConnection(C3P0PooledConnectionPool.java:510)
        at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.refurbishResourceOnCheckin(C3P0PooledConnectionPool.java:406)
        at com.mchange.v2.resourcepool.BasicResourcePool.attemptRefurbishResourceOnCheckin(BasicResourcePool.java:1760)
        at com.mchange.v2.resourcepool.BasicResourcePool.access$200(BasicResourcePool.java:44)
        at com.mchange.v2.resourcepool.BasicResourcePool$1RefurbishCheckinResourceTask.run(BasicResourcePool.java:1378)
        at com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:696)
Caused by: java.lang.NoClassDefFoundError: java/lang/IndyBootstrapDispatcher

which freezes the service.

Strange thing is that everything was working and no changes to this library (dependencies, code, ...) or other updates were made.

JDK used is 1.8.0_201.

Now, I know how to handle this kind of exception, but I have not found any reference to java lang IndyBootstrapDispatcher by crawling sources of the interested libraries.

Any idea? Thank you all.

Jetty is starting with system temp directory for the Java system property java.io.tmpdir.

This is typically the system /tmp directory.

Jetty unpacks wars and accesses deep resources from your webapp from this temp directory.

What happens on some Linux distributions is that the the system temp directory (/tmp) is periodically cleaned up. This can break a running Jetty instance as the content it needs has now been removed out from underneath it.

The key is to use a temp directory for Jetty that isn't the system temp directory.

You can change the temp directory that Jetty uses in a number of ways.

See: https://stackoverflow.com/questions/19232182/jetty-how-to-change-startup-temp-directory

Answering my own question if someone gets here.

This is due to ELK apm connector (version used 1.18.0 RC 1 in auto attach mode); by disabling the agent the errors go away. Further tests will be done on different agent versions.

Relevant GitHub issues here and here.