Since version 2.59 there is a problem when checking out Git repositories on any of our projects. Jenkins seems to hang:

Fetching changes from the remote Git repository

Cleaning workspace

...and that's it.

When looking into the Jenkins logs I see the following exception:

May 08, 2017 11:34:47 AM hudson.init.impl.InstallUncaughtExceptionHandler$DefaultUncaughtExceptionHandler uncaughtException SEVERE: A thread (Thread-17/172) died unexpectedly due to an uncaught exception, this may leave your Jenkins in a bad way and is usually indicative of a bug in the code. java.lang.NullPointerException at com.trilead.ssh2.transport.KexManager.handleMessage(KexManager.java:447) at com.trilead.ssh2.transport.TransportManager.receiveLoop(TransportManager.java:790) at com.trilead.ssh2.transport.TransportManager$1.run(TransportManager.java:502) at java.lang.Thread.run(Thread.java:745)

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Updated from 2.53 to 2.59, updated OpenJDK from 1.7 to 1.8. Jenkins running on Ubuntu 15.