Snap.d error: cannot communicate with server connection refused

– Logs begin at Mon 2019-02-18 17:16:16 UTC, end at Mon 2019-02-18 17:27:08 UTC. –
Feb 18 17:16:25 localhost.localdomain systemd[1]: Starting Snappy daemon…
Feb 18 17:16:26 localhost.localdomain snapd[1088]: AppArmor status: apparmor is enabled and all features are available
Feb 18 17:16:26 localhost.localdomain snapd[1088]: daemon.go:379: started snapd/2.37.1 (series 16) ubuntu-core/16 (armhf) linux/4.4.0-1100-raspi2.
Feb 18 17:16:27 localhost.localdomain systemd[1]: Started Snappy daemon.
Feb 18 17:21:29 localhost.localdomain snapd[1088]: state.go:247: PANIC cannot checkpoint even after 5m0s of retries every 3s: write /var/lib/snapd/state.json.T2wbn2XBCWMr~: no space left on d
Feb 18 17:21:29 localhost.localdomain snapd[1088]: panic: cannot checkpoint even after 5m0s of retries every 3s: write /var/lib/snapd/state.json.T2wbn2XBCWMr~: no space left on device
Feb 18 17:21:29 localhost.localdomain snapd[1088]: panic: internal error: accessing state without lock [recovered]
Feb 18 17:21:29 localhost.localdomain snapd[1088]: panic: internal error: accessing state without lock
Feb 18 17:21:29 localhost.localdomain snapd[1088]: panic: sync: unlock of unlocked mutex
Feb 18 17:21:29 localhost.localdomain snapd[1088]: goroutine 21 [running]:
Feb 18 17:21:29 localhost.localdomain snapd[1088]: panic(0x1031ea0, 0x11a74078)
Feb 18 17:21:29 localhost.localdomain snapd[1088]: /usr/lib/go-1.6/src/runtime/panic.go:481 +0x370
Feb 18 17:21:29 localhost.localdomain snapd[1088]: sync.(*Mutex).Unlock(0x118c4280)
Feb 18 17:21:29 localhost.localdomain snapd[1088]: /usr/lib/go-1.6/src/sync/mutex.go:109 +0xa0
Feb 18 17:21:29 localhost.localdomain snapd[1088]: github.com/snapcore/snapd/overlord/state.(*State).unlock(0x118c4280)
Feb 18 17:21:29 localhost.localdomain snapd[1088]: /build/snapd-AyZ5nb/snapd-2.37.1/_build/src/github.com/snapcore/snapd/overlord/state/state.go:157 +0x58
Feb 18 17:21:29 localhost.localdomain snapd[1088]: panic(0x1031ea0, 0x11a74068)
Feb 18 17:21:29 localhost.localdomain snapd[1088]: /usr/lib/go-1.6/src/runtime/panic.go:443 +0x490
Feb 18 17:21:29 localhost.localdomain snapd[1088]: encoding/json.(*encodeState).marshal.func1(0x1174964c)
Feb 18 17:21:29 localhost.localdomain snapd[1088]: /usr/lib/go-1.6/src/encoding/json/encode.go:269 +0x104
Feb 18 17:21:29 localhost.localdomain snapd[1088]: panic(0x1031ea0, 0x11a74060)
Feb 18 17:21:29 localhost.localdomain snapd[1088]: /usr/lib/go-1.6/src/runtime/panic.go:443 +0x490
Feb 18 17:21:29 localhost.localdomain snapd[1088]: github.com/snapcore/snapd/overlord/state.(*State).reading(0x118c4280)
Feb 18 17:21:29 localhost.localdomain snapd[1088]: /build/snapd-AyZ5nb/snapd-2.37.1/_build/src/github.com/snapcore/snapd/overlord/state/state.go:144 +0x94
Feb 18 17:21:29 localhost.localdomain snapd[1088]: github.com/snapcore/snapd/overlord/state.(*State).MarshalJSON(0x118c4280, 0x0, 0x0, 0x0, 0x0, 0x0)
Feb 18 17:21:29 localhost.localdomain snapd[1088]: /build/snapd-AyZ5nb/snapd-2.37.1/_build/src/github.com/snapcore/snapd/overlord/state/state.go:173 +0x38
Feb 18 17:21:29 localhost.localdomain snapd[1088]: encoding/json.marshalerEncoder(0x11b701e0, 0x1176488, 0x118c4280, 0x16, 0x118c4200)
Feb 18 17:21:29 localhost.localdomain snapd[1088]: /usr/lib/go-1.6/src/encoding/json/encode.go:418 +0x100
Feb 18 17:21:29 localhost.localdomain snapd[1088]: encoding/json.(*encodeState).reflectValue(0x11b701e0, 0x1176488, 0x118c4280, 0x16)
Feb 18 17:21:29 localhost.localdomain snapd[1088]: /usr/lib/go-1.6/src/encoding/json/encode.go:301 +0x64
Feb 18 17:21:29 localhost.localdomain snapd[1088]: encoding/json.(*encodeState).marshal(0x11b701e0, 0x1176488, 0x118c4280, 0x0, 0x0)
Feb 18 17:21:29 localhost.localdomain snapd[1088]: /usr/lib/go-1.6/src/encoding/json/encode.go:274 +0xa0
Feb 18 17:21:29 localhost.localdomain snapd[1088]: encoding/json.Marshal(0x1176488, 0x118c4280, 0x0, 0x0, 0x0, 0x0, 0x0)
Feb 18 17:21:29 localhost.localdomain snapd[1088]: /usr/lib/go-1.6/src/encoding/json/encode.go:139 +0x70
Feb 18 17:21:29 localhost.localdomain snapd[1088]: github.com/snapcore/snapd/overlord/state.(*State).checkpointData(0x118c4280, 0x0, 0x0, 0x0)
Feb 18 17:21:29 localhost.localdomain snapd[1088]: /build/snapd-AyZ5nb/snapd-2.37.1/_build/src/github.com/snapcore/snapd/overlord/state/state.go:213 +0x40
Feb 18 17:21:29 localhost.localdomain snapd[1088]: github.com/snapcore/snapd/overlord/state.(*State).Unlock(0x118c4280)
Feb 18 17:21:29 localhost.localdomain snapd[1088]: /build/snapd-AyZ5nb/snapd-2.37.1/_build/src/github.com/snapcore/snapd/overlord/state/state.go:237 +0x70
Feb 18 17:21:29 localhost.localdomain snapd[1088]: panic(0x1031ea0, 0x11a74050)
Feb 18 17:21:29 localhost.localdomain snapd[1088]: /usr/lib/go-1.6/src/runtime/panic.go:443 +0x490
Feb 18 17:21:29 localhost.localdomain snapd[1088]: github.com/snapcore/snapd/logger.Panicf(0x1263c90, 0x37, 0x11749800, 0x3, 0x3)
Feb 18 17:21:29 localhost.localdomain snapd[1088]: /build/snapd-AyZ5nb/snapd-2.37.1/_build/src/github.com/snapcore/snapd/logger/logger.go:67 +0x14c
Feb 18 17:21:29 localhost.localdomain snapd[1088]: github.com/snapcore/snapd/overlord/state.(*State).Unlock(0x118c4280)
Feb 18 17:21:29 localhost.localdomain snapd[1088]: /build/snapd-AyZ5nb/snapd-2.37.1/_build/src/github.com/snapcore/snapd/overlord/state/state.go:247 +0x310
Feb 18 17:21:29 localhost.localdomain snapd[1088]: github.com/snapcore/snapd/overlord/auth.(*authContext).UpdateDeviceAuth(0x119ea340, 0x11afcb70, 0x11b36000, 0x230, 0x11ada1e0, 0x0, 0x0)
Feb 18 17:21:29 localhost.localdomain snapd[1088]: /build/snapd-AyZ5nb/snapd-2.37.1/_build/src/github.com/snapcore/snapd/overlord/auth/auth.go:457 +0x210
Feb 18 17:21:29 localhost.localdomain snapd[1088]: github.com/snapcore/snapd/store.(*Store).refreshDeviceSession(0x119d87e0, 0x11afcb70, 0x0, 0x0)
Feb 18 17:21:29 localhost.localdomain snapd[1088]: /build/snapd-AyZ5nb/snapd-2.37.1/_build/src/github.com/snapcore/snapd/store/store.go:574 +0x2ac
Feb 18 17:21:29 localhost.localdomain snapd[1088]: github.com/snapcore/snapd/store.(*Store).refreshAuth(0x119d87e0, 0x0, 0x76460001, 0x0, 0x0)
Feb 18 17:21:29 localhost.localdomain snapd[1088]: /build/snapd-AyZ5nb/snapd-2.37.1/_build/src/github.com/snapcore/snapd/store/store.go:833 +0x110
Feb 18 17:21:29 localhost.localdomain snapd[1088]: github.com/snapcore/snapd/store.(*Store).SnapAction(0x119d87e0, 0x74ac4198, 0x11a6ca80, 0x11a6e8a0, 0x3, 0x3, 0x11a6fc90, 0x3, 0x4, 0x0, …
Feb 18 17:21:29 localhost.localdomain snapd[1088]: /build/snapd-AyZ5nb/snapd-2.37.1/_build/src/github.com/snapcore/snapd/store/store.go:2065 +0x3c4
Feb 18 17:21:29 localhost.localdomain snapd[1088]: github.com/snapcore/snapd/overlord/snapstate.refreshCandidates(0x74ac4198, 0x11a6ca80, 0x118c4280, 0x0, 0x0, 0x0, 0x0, 0x11a6e870, 0x0, 0x0,
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