diff --git a/beacon_chain/beacon_chain_db.nim b/beacon_chain/beacon_chain_db.nim
index 00b610639..57fc83ae6 100644
--- a/beacon_chain/beacon_chain_db.nim
+++ b/beacon_chain/beacon_chain_db.nim
@@ -137,9 +137,7 @@ type
       ## only recent contract state data (i.e. only recent `deposit_roots`).
     kHashToStateDiff # Obsolete
     kHashToStateOnlyMutableValidators
-    kBackfillBlock
-      ## Pointer to the earliest block that we have backfilled - if this is not
-      ## set, backfill == tail
+    kBackfillBlock # Obsolete, was in `unstable` for a while, but never released
 
   BeaconBlockSummary* = object
     ## Cache of beacon block summaries - during startup when we construct the
@@ -477,7 +475,7 @@ proc close*(db: BeaconchainDB) =
 
   db.db = nil
 
-func toBeaconBlockSummary(v: SomeSomeBeaconBlock): BeaconBlockSummary =
+func toBeaconBlockSummary*(v: SomeSomeBeaconBlock): BeaconBlockSummary =
   BeaconBlockSummary(
     slot: v.slot,
     parent_root: v.parent_root,
@@ -591,9 +589,6 @@ proc putTailBlock*(db: BeaconChainDB, key: Eth2Digest) =
 proc putGenesisBlock*(db: BeaconChainDB, key: Eth2Digest) =
   db.keyValues.putRaw(subkey(kGenesisBlock), key)
 
-proc putBackfillBlock*(db: BeaconChainDB, key: Eth2Digest) =
-  db.keyValues.putRaw(subkey(kBackfillBlock), key)
-
 proc putEth2FinalizedTo*(db: BeaconChainDB,
                          eth1Checkpoint: DepositContractSnapshot) =
   db.keyValues.putSnappySSZ(subkey(kDepositsFinalizedByEth2), eth1Checkpoint)
@@ -797,9 +792,6 @@ proc getGenesisBlock*(db: BeaconChainDB): Opt[Eth2Digest] =
   db.keyValues.getRaw(subkey(kGenesisBlock), Eth2Digest) or
     db.v0.getGenesisBlock()
 
-proc getBackfillBlock*(db: BeaconChainDB): Opt[Eth2Digest] =
-  db.keyValues.getRaw(subkey(kBackfillBlock), Eth2Digest)
-
 proc getEth2FinalizedTo(db: BeaconChainDBV0): Opt[DepositContractSnapshot] =
   result.ok(DepositContractSnapshot())
   let r = db.backend.getSnappySSZ(subkey(kDepositsFinalizedByEth2), result.get)
@@ -856,7 +848,7 @@ iterator getAncestors*(db: BeaconChainDB, root: Eth2Digest):
     yield res
     root = res.message.parent_root
 
-proc loadSummaries(db: BeaconChainDB): Table[Eth2Digest, BeaconBlockSummary] =
+proc loadSummaries*(db: BeaconChainDB): Table[Eth2Digest, BeaconBlockSummary] =
   # Load summaries into table - there's no telling what order they're in so we
   # load them all - bugs in nim prevent this code from living in the iterator.
   var summaries = initTable[Eth2Digest, BeaconBlockSummary](1024*1024)
diff --git a/beacon_chain/consensus_object_pools/block_clearance.nim b/beacon_chain/consensus_object_pools/block_clearance.nim
index 943be00ae..b5d66aa5e 100644
--- a/beacon_chain/consensus_object_pools/block_clearance.nim
+++ b/beacon_chain/consensus_object_pools/block_clearance.nim
@@ -273,7 +273,7 @@ proc addBackfillBlock*(
   logScope:
     blockRoot = shortLog(signedBlock.root)
     blck = shortLog(signedBlock.message)
-    backfill = (dag.backfill.slot, shortLog(dag.backfill.root))
+    backfill = (dag.backfill.slot, shortLog(dag.backfill.parent_root))
 
   template blck(): untyped = signedBlock.message # shortcuts without copy
   template blockRoot(): untyped = signedBlock.root
@@ -292,7 +292,7 @@ proc addBackfillBlock*(
     debug "Block unviable or duplicate"
     return err(BlockError.UnviableFork)
 
-  if dag.backfill.root != signedBlock.root:
+  if dag.backfill.parent_root != signedBlock.root:
     debug "Block does not match expected backfill root"
     return err(BlockError.MissingParent) # MissingChild really, but ..
 
@@ -319,8 +319,7 @@ proc addBackfillBlock*(
     return err(BlockError.Invalid)
 
   dag.putBlock(signedBlock.asTrusted())
-  dag.db.putBackfillBlock(signedBlock.root)
-  dag.backfill = (blck.slot, blck.parent_root)
+  dag.backfill = blck.toBeaconBlockSummary()
 
   # Invariants maintained on startup
   doAssert dag.backfillBlocks.lenu64 == dag.tail.slot.uint64
diff --git a/beacon_chain/consensus_object_pools/block_pools_types.nim b/beacon_chain/consensus_object_pools/block_pools_types.nim
index ee2607629..245399083 100644
--- a/beacon_chain/consensus_object_pools/block_pools_types.nim
+++ b/beacon_chain/consensus_object_pools/block_pools_types.nim
@@ -113,14 +113,9 @@ type
     ## go - the tail block is unique in that its parent is set to `nil`, even
     ## in the case where a later genesis block exists.
 
-    backfill*: tuple[slot: Slot, root: Eth2Digest] ##\
-    ## The backfill is root of the parent of the the earliest block that we
-    ## have synced, when performing a checkpoint sync start. Because the
-    ## `tail` BlockRef does not have a parent, we store here the root of the
-    ## block we're expecting during backfill.
-    ## When starting a checkpoint sync, `backfill` == `tail.parent_root` - we
-    ## then sync backards, moving the backfill (but not tail!) until we hit
-    ## genesis at which point we set backfill to the zero hash.
+    backfill*: BeaconBlockSummary ##\
+    ## The backfill points to the oldest block that we have, in the database -
+    ## when backfilling, we'll be fetching its parent first
 
     heads*: seq[BlockRef] ##\
     ## Candidate heads of candidate chains
diff --git a/beacon_chain/consensus_object_pools/blockchain_dag.nim b/beacon_chain/consensus_object_pools/blockchain_dag.nim
index 2583cece0..5abe1c5f8 100644
--- a/beacon_chain/consensus_object_pools/blockchain_dag.nim
+++ b/beacon_chain/consensus_object_pools/blockchain_dag.nim
@@ -354,7 +354,6 @@ proc init*(T: type ChainDAGRef, cfg: RuntimeConfig, db: BeaconChainDB,
   let
     tailBlockRoot = db.getTailBlock()
     headBlockRoot = db.getHeadBlock()
-    backfillBlockRoot = db.getBackfillBlock()
 
   doAssert tailBlockRoot.isSome(), "Missing tail block, database corrupt?"
   doAssert headBlockRoot.isSome(), "Missing head block, database corrupt?"
@@ -375,18 +374,6 @@ proc init*(T: type ChainDAGRef, cfg: RuntimeConfig, db: BeaconChainDB,
         "preInit should have initialized the database with a genesis block")
     withBlck(genesisBlock): BlockRef.init(genesisBlockRoot, blck.message)
 
-  let backfill =
-    if backfillBlockRoot.isSome():
-      let backfillBlock = db.getForkedBlock(backfillBlockRoot.get()).expect(
-        "backfill block must be present in database, database corrupt?")
-      (getForkedBlockField(backfillBlock, slot),
-        getForkedBlockField(backfillBlock, parentRoot))
-    elif tailRef.slot > GENESIS_SLOT:
-      (getForkedBlockField(tailBlock, slot),
-        getForkedBlockField(tailBlock, parentRoot))
-    else:
-      (GENESIS_SLOT, Eth2Digest())
-
   var
     blocks: HashSet[KeyedBlockRef]
     headRef: BlockRef
@@ -399,11 +386,15 @@ proc init*(T: type ChainDAGRef, cfg: RuntimeConfig, db: BeaconChainDB,
   var
     backfillBlocks = newSeq[Eth2Digest](tailRef.slot.int)
     curRef: BlockRef
+    backfill = BeaconBlockSummary(slot: GENESIS_SLOT)
 
   for blck in db.getAncestorSummaries(headRoot):
     if blck.summary.slot < tailRef.slot:
       backfillBlocks[blck.summary.slot.int] = blck.root
+      backfill = blck.summary
     elif blck.summary.slot == tailRef.slot:
+      backfill = blck.summary
+
       if curRef == nil:
         curRef = tailRef
         headRef = tailRef
@@ -564,7 +555,7 @@ proc init*(T: type ChainDAGRef, cfg: RuntimeConfig, db: BeaconChainDB,
     finalizedHead = shortLog(dag.finalizedHead),
     tail = shortLog(dag.tail),
     totalBlocks = dag.blocks.len(),
-    backfill = (dag.backfill.slot, shortLog(dag.backfill.root))
+    backfill = (dag.backfill.slot, shortLog(dag.backfill.parent_root))
 
   dag
 
@@ -1386,33 +1377,45 @@ proc updateHead*(
         dag.finalizedHead.slot.epoch)
       dag.onFinHappened(data)
 
-proc isInitialized*(T: type ChainDAGRef, db: BeaconChainDB): bool =
+proc isInitialized*(T: type ChainDAGRef, db: BeaconChainDB): Result[void, cstring] =
   # Lightweight check to see if we have the minimal information needed to
   # load up a database - we don't check head here - if something is wrong with
   # head, it's likely an initialized, but corrupt database - init will detect
   # that
   let
     genesisBlockRoot = db.getGenesisBlock()
-    tailBlockRoot = db.getTailBlock()
 
-  if not (genesisBlockRoot.isSome() and tailBlockRoot.isSome()):
-    return false
+  if not genesisBlockRoot.isSome():
+    return err("Genesis block root missing")
 
   let
     genesisBlock = db.getForkedBlock(genesisBlockRoot.get())
-    tailBlock = db.getForkedBlock(tailBlockRoot.get())
+  if not genesisBlock.isSome():
+    return err("Genesis block missing")
 
-  if not (genesisBlock.isSome() and tailBlock.isSome()):
-    return false
   let
     genesisStateRoot = withBlck(genesisBlock.get()): blck.message.state_root
+
+  if not db.containsState(genesisStateRoot):
+    return err("Genesis state missing")
+
+  let
+    tailBlockRoot = db.getTailBlock()
+  if not tailBlockRoot.isSome():
+    return err("Tail block root missing")
+
+  let
+    tailBlock = db.getForkedBlock(tailBlockRoot.get())
+  if not tailBlock.isSome():
+    return err("Tail block missing")
+
+  let
     tailStateRoot = withBlck(tailBlock.get()): blck.message.state_root
 
-  if not (
-      db.containsState(genesisStateRoot) and db.containsState(tailStateRoot)):
-    return false
+  if not db.containsState(tailStateRoot):
+    return err("Tail state missing")
 
-  true
+  ok()
 
 proc preInit*(
     T: type ChainDAGRef, db: BeaconChainDB,
diff --git a/tests/all_tests.nim.cfg b/beacon_chain/nim.cfg
similarity index 100%
rename from tests/all_tests.nim.cfg
rename to beacon_chain/nim.cfg
diff --git a/beacon_chain/nimbus_beacon_node.nim b/beacon_chain/nimbus_beacon_node.nim
index 951782dd9..fa685e63b 100644
--- a/beacon_chain/nimbus_beacon_node.nim
+++ b/beacon_chain/nimbus_beacon_node.nim
@@ -199,7 +199,7 @@ proc init(T: type BeaconNode,
     quit 1
 
   var eth1Monitor: Eth1Monitor
-  if not ChainDAGRef.isInitialized(db):
+  if not ChainDAGRef.isInitialized(db).isOk():
     var
       tailState: ref ForkedHashedBeaconState
       tailBlock: ForkedTrustedSignedBeaconBlock
@@ -279,7 +279,7 @@ proc init(T: type BeaconNode,
 
     try:
       ChainDAGRef.preInit(db, genesisState[], tailState[], tailBlock)
-      doAssert ChainDAGRef.isInitialized(db), "preInit should have initialized db"
+      doAssert ChainDAGRef.isInitialized(db).isOk(), "preInit should have initialized db"
     except CatchableError as exc:
       error "Failed to initialize database", err = exc.msg
       quit 1
diff --git a/beacon_chain/nimbus_beacon_node.nim.cfg b/beacon_chain/nimbus_beacon_node.nim.cfg
index f61b54a93..4c0d44247 100644
--- a/beacon_chain/nimbus_beacon_node.nim.cfg
+++ b/beacon_chain/nimbus_beacon_node.nim.cfg
@@ -5,6 +5,3 @@
 @if release:
   -d:"chronicles_line_numbers:0"
 @end
-
-# Use only `secp256k1` public key cryptography as an identity in LibP2P.
--d:"libp2p_pki_schemes=secp256k1"
diff --git a/beacon_chain/nimbus_signing_node.nim.cfg b/beacon_chain/nimbus_signing_node.nim.cfg
index f61b54a93..4c0d44247 100644
--- a/beacon_chain/nimbus_signing_node.nim.cfg
+++ b/beacon_chain/nimbus_signing_node.nim.cfg
@@ -5,6 +5,3 @@
 @if release:
   -d:"chronicles_line_numbers:0"
 @end
-
-# Use only `secp256k1` public key cryptography as an identity in LibP2P.
--d:"libp2p_pki_schemes=secp256k1"
diff --git a/beacon_chain/nimbus_validator_client.nim.cfg b/beacon_chain/nimbus_validator_client.nim.cfg
index f61b54a93..4c0d44247 100644
--- a/beacon_chain/nimbus_validator_client.nim.cfg
+++ b/beacon_chain/nimbus_validator_client.nim.cfg
@@ -5,6 +5,3 @@
 @if release:
   -d:"chronicles_line_numbers:0"
 @end
-
-# Use only `secp256k1` public key cryptography as an identity in LibP2P.
--d:"libp2p_pki_schemes=secp256k1"
diff --git a/ncli/ncli_db.nim b/ncli/ncli_db.nim
index 2ac8cd5a4..dd3890e63 100644
--- a/ncli/ncli_db.nim
+++ b/ncli/ncli_db.nim
@@ -195,8 +195,8 @@ proc cmdBench(conf: DbConf, cfg: RuntimeConfig) =
     db.close()
     dbBenchmark.close()
 
-  if not ChainDAGRef.isInitialized(db):
-    echo "Database not initialized"
+  if (let v = ChainDAGRef.isInitialized(db); v.isErr()):
+    echo "Database not initialized: ", v.error()
     quit 1
 
   echo "Initializing block pool..."
@@ -470,8 +470,8 @@ proc cmdRewindState(conf: DbConf, cfg: RuntimeConfig) =
   let db = BeaconChainDB.new(conf.databaseDir.string)
   defer: db.close()
 
-  if not ChainDAGRef.isInitialized(db):
-    echo "Database not initialized"
+  if (let v = ChainDAGRef.isInitialized(db); v.isErr()):
+    echo "Database not initialized: ", v.error()
     quit 1
 
   echo "Initializing block pool..."
@@ -501,8 +501,8 @@ proc cmdExportEra(conf: DbConf, cfg: RuntimeConfig) =
   let db = BeaconChainDB.new(conf.databaseDir.string)
   defer: db.close()
 
-  if not ChainDAGRef.isInitialized(db):
-    echo "Database not initialized"
+  if (let v = ChainDAGRef.isInitialized(db); v.isErr()):
+    echo "Database not initialized: ", v.error()
     quit 1
 
   echo "Initializing block pool..."
@@ -565,8 +565,8 @@ proc cmdValidatorPerf(conf: DbConf, cfg: RuntimeConfig) =
   defer:
     db.close()
 
-  if not ChainDAGRef.isInitialized(db):
-    echo "Database not initialized"
+  if (let v = ChainDAGRef.isInitialized(db); v.isErr()):
+    echo "Database not initialized: ", v.error()
     quit 1
 
   echo "# Initializing block pool..."
@@ -705,8 +705,8 @@ proc cmdValidatorDb(conf: DbConf, cfg: RuntimeConfig) =
   defer:
     db.close()
 
-  if not ChainDAGRef.isInitialized(db):
-    echo "Database not initialized"
+  if (let v = ChainDAGRef.isInitialized(db); v.isErr()):
+    echo "Database not initialized: ", v.error()
     quit 1
 
   echo "Initializing block pool..."
diff --git a/tests/nim.cfg b/tests/nim.cfg
new file mode 100644
index 000000000..e233b3ddc
--- /dev/null
+++ b/tests/nim.cfg
@@ -0,0 +1,2 @@
+# Use only `secp256k1` public key cryptography as an identity in LibP2P.
+-d:"libp2p_pki_schemes=secp256k1"
diff --git a/tests/test_sync_manager.nim.cfg b/tests/test_sync_manager.nim.cfg
deleted file mode 100644
index e88af1eb3..000000000
--- a/tests/test_sync_manager.nim.cfg
+++ /dev/null
@@ -1 +0,0 @@
--d:"libp2p_pki_schemes=secp256k1"