SystemError: unknown opcode when scatter/gather /pull/push

I am running a cluster with Linux/windows machines.

I cannot any longer use scatter/gather/pull/push variables.

In windows this is the error the engines print in the screen

`[1;31m---------------------------------------------------------------------------
[1;31mSystemError Traceback (most recent call last)
[1;32m in ()

[1;32m/home/julian/anaconda3/lib/python3.5/site-packages/ipyparallel/util.py in _pull(keys)

[1;31mSystemError: unknown opcode2017-06-01 20:01:09.640 [IPEngineApp] Exception in apply request:
[1;31m---------------------------------------------------------------------------
[1;31mSystemError Traceback (most recent call last)
[1;32m in ()

[1;32m/home/julian/anaconda3/lib/python3.5/site-packages/ipyparallel/util.py in _pull(keys)

[1;31mSystemError: unknown opcode

`
On linux it generates a seg fault.

On the session I am using as a console (linux) I get the following

`In [6]: dview["qwerty"]=33

In [7]: dview["qwerty"]
[0:apply]:
---------------------------------------------------------------------------SystemError Traceback (most recent call last) in ()
/home/julian/anaconda3/lib/python3.5/site-packages/ipyparallel/util.py in _pull(keys)
SystemError: unknown opcode

[1:apply]:
---------------------------------------------------------------------------SystemError Traceback (most recent call last) in ()
/home/julian/anaconda3/lib/python3.5/site-packages/ipyparallel/util.py in _pull(keys)
SystemError: unknown opcode

[2:apply]:
---------------------------------------------------------------------------SystemError Traceback (most recent call last) in ()
/home/julian/anaconda3/lib/python3.5/site-packages/ipyparallel/util.py in _pull(keys)
SystemError: unknown opcode

[3:apply]:
---------------------------------------------------------------------------SystemError Traceback (most recent call last) in ()
/home/julian/anaconda3/lib/python3.5/site-packages/ipyparallel/util.py in _pull(keys)
SystemError: unknown opcode
`

I am on python 3.5.2, using ipython 4.0.2 and ipyparallel ( all systems ) 6.0.2

I checked google and this does not look like being reported by anybody else.

This has worked fine in the past. First time I am facing this issue

JC