Comment 8 for bug 1569683

I looked through the logs, the issue seems to be this error. This is a UI surfacing error.

2016-04-13 04:07:33 [-] Error on request (146) node.link_subnet: IP address is already in use.
 Traceback (most recent call last):
   File "/usr/lib/python2.7/threading.py", line 783, in __bootstrap
     self.__bootstrap_inner()
   File "/usr/lib/python2.7/threading.py", line 810, in __bootstrap_inner
     self.run()
   File "/usr/lib/python2.7/threading.py", line 763, in run
     self.__target(*self.__args, **self.__kwargs)
   File "/usr/lib/python2.7/dist-packages/provisioningserver/utils/twisted.py", line 791, in _worker
     return super(ThreadPool, self)._worker()
 --- <exception caught here> ---
   File "/usr/lib/python2.7/dist-packages/twisted/python/threadpool.py", line 191, in _worker
     result = context.call(ctx, function, *args, **kwargs)
   File "/usr/lib/python2.7/dist-packages/twisted/python/context.py", line 118, in callWithContext
     return self.currentContext().callWithContext(ctx, func, *args, **kw)
   File "/usr/lib/python2.7/dist-packages/twisted/python/context.py", line 81, in callWithContext
     return func(*args,**kw)
   File "/usr/lib/python2.7/dist-packages/maasserver/utils/orm.py", line 501, in call_within_transaction
     return func_outside_txn(*args, **kwargs)
   File "/usr/lib/python2.7/dist-packages/maasserver/utils/orm.py", line 328, in retrier
     return func(*args, **kwargs)
   File "/usr/lib/python2.7/dist-packages/django/db/transaction.py", line 339, in inner
     return func(*args, **kwargs)
   File "/usr/lib/python2.7/dist-packages/maasserver/websockets/handlers/node.py", line 1172, in link_subnet
     ip_address=params.get("ip_address", None))
   File "/usr/lib/python2.7/dist-packages/maasserver/models/interface.py", line 1110, in update_link_by_id
     static_ip, mode, subnet, ip_address=ip_address)
   File "/usr/lib/python2.7/dist-packages/maasserver/models/interface.py", line 1088, in update_ip_address
     static_ip, subnet, ip_address=ip_address)
   File "/usr/lib/python2.7/dist-packages/maasserver/models/interface.py", line 1014, in _swap_subnet
     "IP address is already in use.")
 maasserver.exceptions.StaticIPAddressUnavailable: IP address is already in use.