Git 'not responding' after update

[Christoph M]

Hi,

I just updated our Jenkins installation to version 2.59 (from 2.53) for which I had to install Java 8 (also on the agents) since it is used by 2.54 and later.

The Jenkins came up again and seemed to be working but 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)

What causes the problem here? How do I fix this?