I tried to upgrade from 1.605 to 1.614 by downloading .war and restarting. After restart Jenkins is unable to connect to most slaves. /var/log/secure on the slaves shows

after upgrade:
May 21 13:20:32 as8 sshd[15563]: Connection from 10.2.7.121 port 61748
May 21 13:20:35 as8 sshd[15563]: Accepted password for sadm from 10.2.7.121 port 61748 ssh2
May 21 13:20:35 as8 sshd[15933]: subsystem request for sftp
May 21 13:27:43 as8 sshd[19718]: Received disconnect from 10.2.6.3: 11: Closed due to user request.
May 21 13:29:03 as8 sshd[21939]: Connection from 10.2.6.3 port 49943
May 21 13:29:05 as8 sshd[21939]: Accepted password for sadm from 10.2.6.3 port 49943 ssh2
May 21 13:29:06 as8 sshd[22160]: subsystem request for sftp
May 21 13:29:11 as8 sshd[22160]: Received disconnect from 10.2.6.3: 11: Closed due to user request.
May 21 13:29:18 as8 sshd[25679]: Connection from 10.2.6.3 port 50042
May 21 13:29:18 as8 sshd[25679]: Accepted password for sadm from 10.2.6.3 port 50042 ssh2
May 21 13:29:19 as8 sshd[25704]: subsystem request for sftp
May 21 13:29:23 as8 sshd[25704]: Received disconnect from 10.2.6.3: 11: Closed due to user request.

After I revert back to 1.405:

May 21 13:30:15 as8 sshd[7499]: Connection from 10.2.6.3 port 50123
May 21 13:30:16 as8 sshd[7499]: Accepted password for sadm from 10.2.6.3 port 50123 ssh2
May 21 13:30:16 as8 sshd[7502]: subsystem request for sftp

And the slave get connected.

The error in jenkins log looks like this:

[05/21/15 13:58:17] SSH Launch of as8 on as8 failed in 4,973 ms
May 21, 2015 1:58:17 PM hudson.remoting.SynchronousCommandTransport$ReaderThread run
SEVERE: I/O error in channel as8
java.io.IOException: Unexpected termination of the channel
at hudson.remoting.SynchronousCommandTransport$ReaderThread.run(SynchronousCommandTransport.java:50)
Caused by: java.io.EOFException
at java.io.ObjectInputStream$PeekInputStream.readFully(ObjectInputStream.java:2328)
at java.io.ObjectInputStream$BlockDataInputStream.readShort(ObjectInputStream.java:2797)
at java.io.ObjectInputStream.readStreamHeader(ObjectInputStream.java:802)
at java.io.ObjectInputStream.<init>(ObjectInputStream.java:299)
at hudson.remoting.ObjectInputStreamEx.<init>(ObjectInputStreamEx.java:40)
at hudson.remoting.AbstractSynchronousByteArrayCommandTransport.read(AbstractSynchronousByteArrayCommandTransport.java:34)
at hudson.remoting.SynchronousCommandTransport$ReaderThread.run(SynchronousCommandTransport.java:48)