Trying to assign an IP address statically to a device results in builtins.AttributeError: 'NoneType' object has no attribute 'link_subnet'

I Same happens if I try to create a device with 'Dynamic' IP address assignment:

016-03-17 11:36:17 [-] Error on request (51) device.create: 'NoneType' object has no attribute 'link_subnet'
 Traceback (most recent call last):
   File "/usr/lib/python3.5/threading.py", line 862, in run
     self._target(*self._args, **self._kwargs)
   File "/usr/lib/python3/dist-packages/provisioningserver/utils/twisted.py", line 794, in worker
     return target()
   File "/usr/lib/python3/dist-packages/twisted/_threads/_threadworker.py", line 46, in work
     task()
   File "/usr/lib/python3/dist-packages/twisted/_threads/_team.py", line 190, in doWork
     task()
 --- <exception caught here> ---
   File "/usr/lib/python3/dist-packages/twisted/python/threadpool.py", line 246, in inContext
     result = inContext.theWork()
   File "/usr/lib/python3/dist-packages/twisted/python/threadpool.py", line 262, in <lambda>
     inContext.theWork = lambda: context.call(ctx, func, *args, **kw)
   File "/usr/lib/python3/dist-packages/twisted/python/context.py", line 118, in callWithContext
     return self.currentContext().callWithContext(ctx, func, *args, **kw)
   File "/usr/lib/python3/dist-packages/twisted/python/context.py", line 81, in callWithContext
     return func(*args,**kw)
   File "/usr/lib/python3/dist-packages/maasserver/utils/orm.py", line 448, in call_within_transaction
     return func_outside_txn(*args, **kwargs)
   File "/usr/lib/python3/dist-packages/maasserver/utils/orm.py", line 275, in retrier
     return func(*args, **kwargs)
   File "/usr/lib/python3.5/contextlib.py", line 30, in inner
     return func(*args, **kwds)
   File "/usr/lib/python3/dist-packages/maasserver/websockets/handlers/device.py", line 263, in create
     interface.link_subnet(INTERFACE_LINK_TYPE.DHCP, None)
 builtins.AttributeError: 'NoneType' object has no attribute 'link_subnet'

Confirmed.

In a subnet of 192.168.1.0/24 I was able to add a device with address 192.168.1.1 but then experienced this crash with the second device.

Looking at the code there is no reason that the interface should not be set. The only reason would because the interface did not get created. If that is the case the create with the form should raise an exception to tell the user.

Please check the following so I can see how this can be handled better:

Check that the MAC address you provided was unique. If it was not unique it should raise an exception.

Also check for any other logs that might be related to see this issue, like something in maas.log.

Okay, I've figured it out. If the MAC address entered in the UI has uppercase characters then get_Interface_from_list (in m.websockets.handlers.device) will not find the interface in the list.