Comment 9 for bug 1960944

The Kernel team experienced this problem yesterday, Feb 15th.
MAAS Version: MAAS version: 2.9.2 (9164-g.ac176b5c4-0ubuntu1~20.04.1)
Deb Pkg Installation

Here are the logs from the rackd controller at the time this occurred.
There were no obvious warnings/errors/tracebacks in the regiond.log
I restarted maas-rackd and maas-regiond services / updated the boot sources and the problem appears to have resolved itself. Yet, would be nice to know why this happened to begin with.

2022-02-15 15:31:44 provisioningserver.rpc.clusterservice: [critical] Failed to contact region. (While requesting RPC info at http://10.246.72.3:5240/MAAS).
 Traceback (most recent call last):
   File "/usr/lib/python3/dist-packages/twisted/internet/defer.py", line 460, in callback
     self._startRunCallbacks(result)
   File "/usr/lib/python3/dist-packages/twisted/internet/defer.py", line 568, in _startRunCallbacks
     self._runCallbacks()
   File "/usr/lib/python3/dist-packages/twisted/internet/defer.py", line 654, in _runCallbacks
     current.result = callback(current.result, *args, **kw)
   File "/usr/lib/python3/dist-packages/twisted/internet/defer.py", line 1475, in gotResult
     _inlineCallbacks(r, g, status)
 --- <exception caught here> ---
   File "/usr/lib/python3/dist-packages/provisioningserver/rpc/clusterservice.py", line 1367, in _doUpdate
     eventloops, maas_url = yield self._get_rpc_info(urls)
   File "/usr/lib/python3/dist-packages/provisioningserver/rpc/clusterservice.py", line 1631, in _get_rpc_info
     raise config_exc
   File "/usr/lib/python3/dist-packages/provisioningserver/rpc/clusterservice.py", line 1602, in _get_rpc_info
     eventloops, maas_url = yield self._parallel_fetch_rpc_info(urls)
   File "/usr/lib/python3/dist-packages/twisted/internet/defer.py", line 654, in _runCallbacks
     current.result = callback(current.result, *args, **kw)
   File "/usr/lib/python3/dist-packages/provisioningserver/rpc/clusterservice.py", line 1576, in handle_responses
     errors[0].raiseException()
   File "/usr/lib/python3/dist-packages/twisted/python/failure.py", line 467, in raiseException
     raise self.value.with_traceback(self.tb)
   File "/usr/lib/python3/dist-packages/provisioningserver/rpc/clusterservice.py", line 1537, in _serial_fetch_rpc_info
     raise last_exc
   File "/usr/lib/python3/dist-packages/provisioningserver/rpc/clusterservice.py", line 1529, in _serial_fetch_rpc_info
     response = yield self._fetch_rpc_info(url, orig_url)
   File "/usr/lib/python3/dist-packages/twisted/internet/defer.py", line 1416, in _inlineCallbacks
     result = result.throwExceptionIntoGenerator(g)
   File "/usr/lib/python3/dist-packages/twisted/python/failure.py", line 491, in throwExceptionIntoGenerator
     return g.throw(self.type, self.value, self.tb)
   File "/usr/lib/python3/dist-packages/provisioningserver/rpc/clusterservice.py", line 1631, in _get_rpc_info
     raise config_exc
   File "/usr/lib/python3/dist-packages/provisioningserver/rpc/clusterservice.py", line 1602, in _get_rpc_info
     eventloops, maas_url = yield self._parallel_fetch_rpc_info(urls)
   File "/usr/lib/python3/dist-packages/twisted/internet/defer.py", line 654, in _runCallbacks
     current.result = callback(current.result, *args, **kw)
   File "/usr/lib/python3/dist-packages/provisioningserver/rpc/clusterservice.py", line 1576, in handle_responses
     errors[0].raiseException()
   File "/usr/lib/python3/dist-packages/twisted/python/failure.py", line 467, in raiseException
     raise self.value.with_traceback(self.tb)
   File "/usr/lib/python3/dist-packages/twisted/internet/defer.py", line 1416, in _inlineCallbacks
     result = result.throwExceptionIntoGenerator(g)
   File "/usr/lib/python3/dist-packages/twisted/python/failure.py", line 491, in throwExceptionIntoGenerator
     return g.throw(self.type, self.value, self.tb)
   File "/usr/lib/python3/dist-packages/provisioningserver/rpc/clusterservice.py", line 1537, in _serial_fetch_rpc_info
     raise last_exc
   File "/usr/lib/python3/dist-packages/provisioningserver/rpc/clusterservice.py", line 1529, in _serial_fetch_rpc_info
     response = yield self._fetch_rpc_info(url, orig_url)
 twisted.internet.error.ConnectingCancelledError: HostnameAddress(hostname=b'10.246.72.3', port=5240)

2022-02-15 15:33:39 provisioningserver.rpc.clusterservice: [critical] Failed to contact region. (While requesting RPC info at http://10.246.72.3:5240/MAAS).
 Traceback (most recent call last):
   File "/usr/lib/python3/dist-packages/twisted/internet/defer.py", line 460, in callback
     self._startRunCallbacks(result)
   File "/usr/lib/python3/dist-packages/twisted/internet/defer.py", line 568, in _startRunCallbacks
     self._runCallbacks()
   File "/usr/lib/python3/dist-packages/twisted/internet/defer.py", line 654, in _runCallbacks
     current.result = callback(current.result, *args, **kw)
   File "/usr/lib/python3/dist-packages/twisted/internet/defer.py", line 1475, in gotResult
     _inlineCallbacks(r, g, status)
 --- <exception caught here> ---
   File "/usr/lib/python3/dist-packages/provisioningserver/rpc/clusterservice.py", line 1367, in _doUpdate
     eventloops, maas_url = yield self._get_rpc_info(urls)
   File "/usr/lib/python3/dist-packages/provisioningserver/rpc/clusterservice.py", line 1631, in _get_rpc_info
     raise config_exc
   File "/usr/lib/python3/dist-packages/provisioningserver/rpc/clusterservice.py", line 1602, in _get_rpc_info
     eventloops, maas_url = yield self._parallel_fetch_rpc_info(urls)
   File "/usr/lib/python3/dist-packages/twisted/internet/defer.py", line 654, in _runCallbacks
     current.result = callback(current.result, *args, **kw)
   File "/usr/lib/python3/dist-packages/provisioningserver/rpc/clusterservice.py", line 1576, in handle_responses
     errors[0].raiseException()
   File "/usr/lib/python3/dist-packages/twisted/python/failure.py", line 467, in raiseException
     raise self.value.with_traceback(self.tb)
   File "/usr/lib/python3/dist-packages/provisioningserver/rpc/clusterservice.py", line 1537, in _serial_fetch_rpc_info
     raise last_exc
   File "/usr/lib/python3/dist-packages/provisioningserver/rpc/clusterservice.py", line 1529, in _serial_fetch_rpc_info
     response = yield self._fetch_rpc_info(url, orig_url)
   File "/usr/lib/python3/dist-packages/twisted/internet/defer.py", line 1416, in _inlineCallbacks
     result = result.throwExceptionIntoGenerator(g)
   File "/usr/lib/python3/dist-packages/twisted/python/failure.py", line 491, in throwExceptionIntoGenerator
     return g.throw(self.type, self.value, self.tb)
   File "/usr/lib/python3/dist-packages/provisioningserver/rpc/clusterservice.py", line 1631, in _get_rpc_info
     raise config_exc
   File "/usr/lib/python3/dist-packages/provisioningserver/rpc/clusterservice.py", line 1602, in _get_rpc_info
     eventloops, maas_url = yield self._parallel_fetch_rpc_info(urls)
   File "/usr/lib/python3/dist-packages/twisted/internet/defer.py", line 654, in _runCallbacks
     current.result = callback(current.result, *args, **kw)
   File "/usr/lib/python3/dist-packages/provisioningserver/rpc/clusterservice.py", line 1576, in handle_responses
     errors[0].raiseException()
   File "/usr/lib/python3/dist-packages/twisted/python/failure.py", line 467, in raiseException
     raise self.value.with_traceback(self.tb)
   File "/usr/lib/python3/dist-packages/twisted/internet/defer.py", line 1416, in _inlineCallbacks
     result = result.throwExceptionIntoGenerator(g)
   File "/usr/lib/python3/dist-packages/twisted/python/failure.py", line 491, in throwExceptionIntoGenerator
     return g.throw(self.type, self.value, self.tb)
   File "/usr/lib/python3/dist-packages/provisioningserver/rpc/clusterservice.py", line 1537, in _serial_fetch_rpc_info
     raise last_exc
   File "/usr/lib/python3/dist-packages/provisioningserver/rpc/clusterservice.py", line 1529, in _serial_fetch_rpc_info
     response = yield self._fetch_rpc_info(url, orig_url)
 twisted.internet.error.ConnectingCancelledError: HostnameAddress(hostname=b'10.246.72.3', port=5240)