Reconnect minion on a new salt-master causes issues - salt-stack

Question

I'm trying to reconnect minions to my new salt-master.
To do that,
I changed the sources.list
installing the new version of salt-minion (from 2015 to 2017.7.8)
Disconnect the minion from the old salt-master (I had two master to manage the old server because the internal application wasn't
uptodate to run a 2017 version of salt, and one for the uptodate
infrastructure)
I ran rm -r /etc/salt/pki
systemctl force-reload salt-minion.servce
I accepted the key on my new master
I ran salt-call state.sls motd (or whatever the formula)
The point is the following. For few of my minions, I cannot say why, but when I ran the last command salt-call state.sls motd I get this issue:
[ERROR ] An un-handled exception was caught by salt's global exception handler:
KeyError: 'saltutil.is_running'
Traceback (most recent call last):
File "/usr/bin/salt-call", line 11, in <module>
salt_call()
File "/usr/lib/python2.7/dist-packages/salt/scripts.py", line 396, in salt_call
client.run()
File "/usr/lib/python2.7/dist-packages/salt/cli/call.py", line 58, in run
caller.run()
File "/usr/lib/python2.7/dist-packages/salt/cli/caller.py", line 134, in run
ret = self.call()
File "/usr/lib/python2.7/dist-packages/salt/cli/caller.py", line 204, in call
ret['return'] = func(*args, **kwargs)
File "/usr/lib/python2.7/dist-packages/salt/modules/state.py", line 1071, in sls
conflict = running(concurrent)
File "/usr/lib/python2.7/dist-packages/salt/modules/state.py", line 209, in running
active = __salt__['saltutil.is_running']('state.*')
File "/usr/lib/python2.7/dist-packages/salt/loader.py", line 1121, in __getitem__
func = super(LazyLoader, self).__getitem__(item)
File "/usr/lib/python2.7/dist-packages/salt/utils/lazy.py", line 101, in __getitem__
raise KeyError(key)
KeyError: 'saltutil.is_running'
Traceback (most recent call last):
File "/usr/bin/salt-call", line 11, in <module>
salt_call()
File "/usr/lib/python2.7/dist-packages/salt/scripts.py", line 396, in salt_call
client.run()
File "/usr/lib/python2.7/dist-packages/salt/cli/call.py", line 58, in run
caller.run()
File "/usr/lib/python2.7/dist-packages/salt/cli/caller.py", line 134, in run
ret = self.call()
File "/usr/lib/python2.7/dist-packages/salt/cli/caller.py", line 204, in call
ret['return'] = func(*args, **kwargs)
File "/usr/lib/python2.7/dist-packages/salt/modules/state.py", line 1071, in sls
conflict = running(concurrent)
File "/usr/lib/python2.7/dist-packages/salt/modules/state.py", line 209, in running
active = __salt__['saltutil.is_running']('state.*')
File "/usr/lib/python2.7/dist-packages/salt/loader.py", line 1121, in __getitem__
func = super(LazyLoader, self).__getitem__(item)
File "/usr/lib/python2.7/dist-packages/salt/utils/lazy.py", line 101, in __getitem__
raise KeyError(key)
KeyError: 'saltutil.is_running'
My salt version:
Salt Version:
Salt: 2017.7.8
Dependency Versions:
cffi: 0.8.6
cherrypy: Not Installed
dateutil: 2.2
docker-py: Not Installed
gitdb: Not Installed
gitpython: Not Installed
ioflo: Not Installed
Jinja2: 2.7.3
libgit2: Not Installed
libnacl: Not Installed
M2Crypto: 0.21.1
Mako: Not Installed
msgpack-pure: Not Installed
msgpack-python: 0.4.2
mysql-python: 1.2.3
pycparser: 2.10
pycrypto: 2.6.1
pycryptodome: Not Installed
pygit2: Not Installed
Python: 2.7.9 (default, Jun 29 2016, 13:08:31)
python-gnupg: Not Installed
PyYAML: 3.11
PyZMQ: 14.4.0
RAET: Not Installed
smmap: Not Installed
timelib: Not Installed
Tornado: 4.2.1
ZMQ: 4.0.5
System Versions:
dist: debian 8.8
locale: UTF-8
machine: x86_64
release: 3.16.0-4-amd64
system: Linux
version: debian 8.8
I tried to uninstall salt-minion with:
apt-get autoremove salt-minion* -y
apt-get purge salt-minion* -y
aptitude purge salt-minion -y
And apt-get update & install salt-minion
But I still have the exact same error. And not on every minions. For some of them, I have the exact same configuration on each server, and it can work for one and not the other.
Any clue? Help :s