diff --git a/beacon_chain/beacon_node.nim b/beacon_chain/beacon_node.nim
index fda717d1a..6321cf4bd 100644
--- a/beacon_chain/beacon_node.nim
+++ b/beacon_chain/beacon_node.nim
@@ -303,12 +303,13 @@ proc storeBlock(
   let blck = node.blockPool.add(blockRoot, signedBlock)
   if blck.isErr:
     if blck.error == Invalid and node.config.dumpEnabled:
+      dump(node.config.dumpDir / "invalid", signedBlock, blockRoot)
+
       let parent = node.blockPool.getRef(signedBlock.message.parent_root)
       if parent != nil:
-        node.blockPool.withState(
-          node.blockPool.tmpState, parent.atSlot(signedBlock.message.slot - 1)):
+        let parentBs = parent.atSlot(signedBlock.message.slot - 1)
+        node.blockPool.withState(node.blockPool.tmpState, parentBs):
             dump(node.config.dumpDir / "invalid", hashedState, parent)
-            dump(node.config.dumpDir / "invalid", signedBlock, blockRoot)
 
     return err(blck.error)
 
@@ -1082,6 +1083,7 @@ programMain:
     if config.dumpEnabled:
       createDir(config.dumpDir)
       createDir(config.dumpDir / "incoming")
+      createDir(config.dumpDir / "invalid")
 
     var node = waitFor BeaconNode.init(config)
 
diff --git a/beacon_chain/block_pools/candidate_chains.nim b/beacon_chain/block_pools/candidate_chains.nim
index 7b4eef987..2da450573 100644
--- a/beacon_chain/block_pools/candidate_chains.nim
+++ b/beacon_chain/block_pools/candidate_chains.nim
@@ -313,12 +313,50 @@ proc getState(
 
 func getStateCacheIndex(dag: CandidateChains, blockRoot: Eth2Digest, slot: Slot): int =
   for i, cachedState in dag.cachedStates:
-    let (cacheBlockRoot, cacheSlot, state) = cachedState
+    let (cacheBlockRoot, cacheSlot, _) = cachedState
     if cacheBlockRoot == blockRoot and cacheSlot == slot:
       return i
 
   -1
 
+func putStateCache(
+    dag: CandidateChains, state: HashedBeaconState, blck: BlockRef) =
+  # Need to be able to efficiently access states for both attestation
+  # aggregation and to process block proposals going back to the last
+  # finalized slot. Ideally to avoid potential combinatiorial forking
+  # storage and/or memory constraints could CoW, up to and including,
+  # in particular, hash_tree_root() which is expensive to do 30 times
+  # since the previous epoch, to efficiently state_transition back to
+  # desired slot. However, none of that's in place, so there are both
+  # expensive, repeated BeaconState copies as well as computationally
+  # time-consuming-near-end-of-epoch hash tree roots. The latter are,
+  # effectively, naïvely O(n^2) in slot number otherwise, so when the
+  # slots become in the mid-to-high-20s it's spending all its time in
+  # pointlessly repeated calculations of prefix-state-transitions. An
+  # intermediate time/memory workaround involves storing only mapping
+  # between BlockRefs, or BlockSlots, and the BeaconState tree roots,
+  # but that still involves tens of megabytes worth of copying, along
+  # with the concomitant memory allocator and GC load. Instead, use a
+  # more memory-intensive (but more conceptually straightforward, and
+  # faster) strategy to just store, for the most recent slots.
+  let stateCacheIndex = dag.getStateCacheIndex(blck.root, state.data.slot)
+  if stateCacheIndex == -1:
+    # Could use a deque or similar, but want simpler structure, and the data
+    # items are small and few.
+    const MAX_CACHE_SIZE = 32
+
+    let cacheLen = dag.cachedStates.len
+    doAssert cacheLen <= MAX_CACHE_SIZE
+
+    let entry =
+      if dag.cachedStates.len == MAX_CACHE_SIZE: dag.cachedStates.pop().state
+      else: (ref HashedBeaconState)()
+    entry[] = state
+
+    insert(dag.cachedStates, (blck.root, state.data.slot, entry))
+    trace "CandidateChains.putState(): state cache updated",
+      cacheLen, root = shortLog(blck.root), slot = state.data.slot
+
 proc putState*(dag: CandidateChains, state: HashedBeaconState, blck: BlockRef) =
   # TODO we save state at every epoch start but never remove them - we also
   #      potentially save multiple states per slot if reorgs happen, meaning
@@ -344,35 +382,7 @@ proc putState*(dag: CandidateChains, state: HashedBeaconState, blck: BlockRef) =
       if not rootWritten:
         dag.db.putStateRoot(blck.root, state.data.slot, state.root)
 
-  # Need to be able to efficiently access states for both attestation
-  # aggregation and to process block proposals going back to the last
-  # finalized slot. Ideally to avoid potential combinatiorial forking
-  # storage and/or memory constraints could CoW, up to and including,
-  # in particular, hash_tree_root() which is expensive to do 30 times
-  # since the previous epoch, to efficiently state_transition back to
-  # desired slot. However, none of that's in place, so there are both
-  # expensive, repeated BeaconState copies as well as computationally
-  # time-consuming-near-end-of-epoch hash tree roots. The latter are,
-  # effectively, naïvely O(n^2) in slot number otherwise, so when the
-  # slots become in the mid-to-high-20s it's spending all its time in
-  # pointlessly repeated calculations of prefix-state-transitions. An
-  # intermediate time/memory workaround involves storing only mapping
-  # between BlockRefs, or BlockSlots, and the BeaconState tree roots,
-  # but that still involves tens of megabytes worth of copying, along
-  # with the concomitant memory allocator and GC load. Instead, use a
-  # more memory-intensive (but more conceptually straightforward, and
-  # faster) strategy to just store, for the most recent slots.
-  let stateCacheIndex = dag.getStateCacheIndex(blck.root, state.data.slot)
-  if stateCacheIndex == -1:
-    # Could use a deque or similar, but want simpler structure, and the data
-    # items are small and few.
-    const MAX_CACHE_SIZE = 32
-    insert(dag.cachedStates, (blck.root, state.data.slot, newClone(state)))
-    while dag.cachedStates.len > MAX_CACHE_SIZE:
-      discard dag.cachedStates.pop()
-    let cacheLen = dag.cachedStates.len
-    trace "CandidateChains.putState(): state cache updated", cacheLen
-    doAssert cacheLen > 0 and cacheLen <= MAX_CACHE_SIZE
+  putStateCache(dag, state, blck)
 
 func getRef*(dag: CandidateChains, root: Eth2Digest): BlockRef =
   ## Retrieve a resolved block reference, if available
diff --git a/beacon_chain/block_pools/clearance.nim b/beacon_chain/block_pools/clearance.nim
index 2e7e35645..79d8f083d 100644
--- a/beacon_chain/block_pools/clearance.nim
+++ b/beacon_chain/block_pools/clearance.nim
@@ -266,7 +266,9 @@ proc isValidBeaconBlock*(
   # The block is not from a future slot
   # TODO allow `MAXIMUM_GOSSIP_CLOCK_DISPARITY` leniency, especially towards
   # seemingly future slots.
-  if not (signed_beacon_block.message.slot <= current_slot):
+  # TODO using +1 here while this is being sorted - should queue these until
+  #      they're within the DISPARITY limit
+  if not (signed_beacon_block.message.slot <= current_slot + 1):
     debug "isValidBeaconBlock: block is from a future slot",
       signed_beacon_block_message_slot = signed_beacon_block.message.slot,
       current_slot = current_slot
diff --git a/beacon_chain/spec/beaconstate.nim b/beacon_chain/spec/beaconstate.nim
index dfec56815..cbb722988 100644
--- a/beacon_chain/spec/beaconstate.nim
+++ b/beacon_chain/spec/beaconstate.nim
@@ -174,7 +174,7 @@ proc slash_validator*(state: var BeaconState, slashed_index: ValidatorIndex,
   validator.slashed = true
   validator.withdrawable_epoch =
     max(validator.withdrawable_epoch, epoch + EPOCHS_PER_SLASHINGS_VECTOR)
-  state.slashings[epoch mod EPOCHS_PER_SLASHINGS_VECTOR] +=
+  state.slashings[int(epoch mod EPOCHS_PER_SLASHINGS_VECTOR)] +=
     validator.effective_balance
   decrease_balance(state, slashed_index,
     validator.effective_balance div MIN_SLASHING_PENALTY_QUOTIENT)
diff --git a/beacon_chain/spec/state_transition_epoch.nim b/beacon_chain/spec/state_transition_epoch.nim
index 6bc05e1e2..467872f85 100644
--- a/beacon_chain/spec/state_transition_epoch.nim
+++ b/beacon_chain/spec/state_transition_epoch.nim
@@ -566,7 +566,7 @@ func process_final_updates*(state: var BeaconState) {.nbench.}=
           MAX_EFFECTIVE_BALANCE)
 
   # Reset slashings
-  state.slashings[next_epoch mod EPOCHS_PER_SLASHINGS_VECTOR] = 0.Gwei
+  state.slashings[int(next_epoch mod EPOCHS_PER_SLASHINGS_VECTOR)] = 0.Gwei
 
   # Set randao mix
   state.randao_mixes[next_epoch mod EPOCHS_PER_HISTORICAL_VECTOR] =
diff --git a/beacon_chain/sszdump.nim b/beacon_chain/sszdump.nim
index dbd1a7151..1268fd591 100644
--- a/beacon_chain/sszdump.nim
+++ b/beacon_chain/sszdump.nim
@@ -1,24 +1,38 @@
+{.push raises: [Defect].}
+
 import
-  os, strformat,
+  os, strformat, chronicles,
   ssz/ssz_serialization,
   beacon_node_types,
   ./spec/[crypto, datatypes, digest]
 
+# Dump errors are generally not fatal where used currently - the code calling
+# these functions, like most code, is not exception safe
+template logErrors(body: untyped) =
+  try:
+    body
+  except CatchableError as err:
+    notice "Failed to write SSZ", dir, msg = err.msg
+
 proc dump*(dir: string, v: AttestationData, validator: ValidatorPubKey) =
-  SSZ.saveFile(dir / &"att-{v.slot}-{v.index}-{shortLog(validator)}.ssz", v)
+  logErrors:
+    SSZ.saveFile(dir / &"att-{v.slot}-{v.index}-{shortLog(validator)}.ssz", v)
 
 proc dump*(dir: string, v: SignedBeaconBlock, root: Eth2Digest) =
-  SSZ.saveFile(dir / &"block-{v.message.slot}-{shortLog(root)}.ssz", v)
+  logErrors:
+    SSZ.saveFile(dir / &"block-{v.message.slot}-{shortLog(root)}.ssz", v)
 
 proc dump*(dir: string, v: SignedBeaconBlock, blck: BlockRef) =
   dump(dir, v, blck.root)
 
 proc dump*(dir: string, v: HashedBeaconState, blck: BlockRef) =
-  SSZ.saveFile(
-    dir / &"state-{v.data.slot}-{shortLog(blck.root)}-{shortLog(v.root)}.ssz",
-    v.data)
+  logErrors:
+    SSZ.saveFile(
+      dir / &"state-{v.data.slot}-{shortLog(blck.root)}-{shortLog(v.root)}.ssz",
+      v.data)
 
 proc dump*(dir: string, v: HashedBeaconState) =
-  SSZ.saveFile(
-    dir / &"state-{v.data.slot}-{shortLog(v.root)}.ssz",
-    v.data)
+  logErrors:
+    SSZ.saveFile(
+      dir / &"state-{v.data.slot}-{shortLog(v.root)}.ssz",
+      v.data)
diff --git a/ncli/ncli_hash_tree_root.nim b/ncli/ncli_hash_tree_root.nim
index 2a91a4074..24260880a 100644
--- a/ncli/ncli_hash_tree_root.nim
+++ b/ncli/ncli_hash_tree_root.nim
@@ -17,13 +17,17 @@ cli do(kind: string, file: string):
         echo "Unknown file type: ", ext
         quit 1
     )
-    echo hash_tree_root(v[]).data.toHex()
+    when t is SignedBeaconBlock:
+      echo hash_tree_root(v.message).data.toHex()
+    else:
+      echo hash_tree_root(v[]).data.toHex()
 
   let ext = splitFile(file).ext
 
   case kind
   of "attester_slashing": printit(AttesterSlashing)
   of "attestation": printit(Attestation)
+  of "signed_block": printit(SignedBeaconBlock)
   of "block": printit(BeaconBlock)
   of "block_body": printit(BeaconBlockBody)
   of "block_header": printit(BeaconBlockHeader)
diff --git a/ncli/ncli_pretty.nim b/ncli/ncli_pretty.nim
index 80462da11..b6dac732b 100644
--- a/ncli/ncli_pretty.nim
+++ b/ncli/ncli_pretty.nim
@@ -22,6 +22,7 @@ cli do(kind: string, file: string):
   case kind
   of "attester_slashing": printit(AttesterSlashing)
   of "attestation": printit(Attestation)
+  of "signed_block": printit(SignedBeaconBlock)
   of "block": printit(BeaconBlock)
   of "block_body": printit(BeaconBlockBody)
   of "block_header": printit(BeaconBlockHeader)
diff --git a/tests/test_block_pool.nim b/tests/test_block_pool.nim
index 18cd986b7..53f1509be 100644
--- a/tests/test_block_pool.nim
+++ b/tests/test_block_pool.nim
@@ -13,6 +13,9 @@ import
   ../beacon_chain/spec/[datatypes, digest, validator],
   ../beacon_chain/[beacon_node_types, block_pool, state_transition, ssz]
 
+when isMainModule:
+  import chronicles # or some random compile error happens...
+
 suiteReport "BlockRef and helpers" & preset():
   timedTest "isAncestorOf sanity" & preset():
     let
@@ -367,3 +370,4 @@ when const_preset == "minimal":  # These require some minutes in mainnet
           hash_tree_root(pool.headState.data.data)
         hash_tree_root(pool2.justifiedState.data.data) ==
           hash_tree_root(pool.justifiedState.data.data)
+