diff --git a/coordinator/purger.go b/coordinator/purger.go
index 21e21fc..fa0256d 100644
--- a/coordinator/purger.go
+++ b/coordinator/purger.go
@@ -133,9 +133,11 @@ func poolMarkInvalidOldNonces(l2DB *l2db.L2DB, stateDB *statedb.LocalStateDB,
 			if tracerr.Unwrap(err) != db.ErrNotFound {
 				return tracerr.Wrap(err)
 			} else if idx <= lastIdx {
-				return tracerr.Wrap(fmt.Errorf("account with idx %v not found: %w", idx, err))
+				return tracerr.Wrap(fmt.Errorf("account with idx %v (lastIdx: %v) "+
+					"not found: %w", idx, lastIdx, err))
 			} else {
-				return tracerr.Wrap(fmt.Errorf("unexpected stateDB error with idx %v: %w", idx, err))
+				return tracerr.Wrap(fmt.Errorf("unexpected stateDB error with idx %v "+
+					"(lastIdx: %v): %w", idx, lastIdx, err))
 			}
 		}
 		idxsNonce[i].Idx = idx
diff --git a/db/kvdb/kvdb.go b/db/kvdb/kvdb.go
index b136f0e..88d9c60 100644
--- a/db/kvdb/kvdb.go
+++ b/db/kvdb/kvdb.go
@@ -135,7 +135,7 @@ func (kvdb *KVDB) reset(batchNum common.BatchNum, closeCurrent bool) error {
 			return tracerr.Wrap(err)
 		}
 		kvdb.db = sto
-		kvdb.CurrentIdx = 255
+		kvdb.CurrentIdx = common.RollupConstReservedIDx // 255
 		kvdb.CurrentBatch = 0
 
 		return nil
@@ -204,7 +204,7 @@ func (kvdb *KVDB) ResetFromSynchronizer(batchNum common.BatchNum, synchronizerKV
 			return tracerr.Wrap(err)
 		}
 		kvdb.db = sto
-		kvdb.CurrentIdx = 255
+		kvdb.CurrentIdx = common.RollupConstReservedIDx // 255
 		kvdb.CurrentBatch = 0
 
 		return nil
@@ -286,7 +286,7 @@ func (kvdb *KVDB) setCurrentBatch() error {
 func (kvdb *KVDB) GetCurrentIdx() (common.Idx, error) {
 	idxBytes, err := kvdb.db.Get(keyCurrentIdx)
 	if tracerr.Unwrap(err) == db.ErrNotFound {
-		return 0, nil
+		return common.RollupConstReservedIDx, nil // 255, nil
 	}
 	if err != nil {
 		return 0, tracerr.Wrap(err)
@@ -442,3 +442,8 @@ func pebbleMakeCheckpoint(source, dest string) error {
 
 	return nil
 }
+
+// Close the DB
+func (kvdb *KVDB) Close() {
+	kvdb.db.Close()
+}
diff --git a/db/kvdb/kvdb_test.go b/db/kvdb/kvdb_test.go
index 16d201e..f50b685 100644
--- a/db/kvdb/kvdb_test.go
+++ b/db/kvdb/kvdb_test.go
@@ -195,3 +195,42 @@ func TestDeleteOldCheckpoints(t *testing.T) {
 		assert.LessOrEqual(t, len(checkpoints), keep)
 	}
 }
+
+func TestGetCurrentIdx(t *testing.T) {
+	dir, err := ioutil.TempDir("", "tmpdb")
+	require.NoError(t, err)
+	defer require.NoError(t, os.RemoveAll(dir))
+
+	keep := 16
+	db, err := NewKVDB(dir, keep)
+	require.NoError(t, err)
+
+	idx, err := db.GetCurrentIdx()
+	require.NoError(t, err)
+	assert.Equal(t, common.Idx(255), idx)
+
+	db.Close()
+
+	db, err = NewKVDB(dir, keep)
+	require.NoError(t, err)
+
+	idx, err = db.GetCurrentIdx()
+	require.NoError(t, err)
+	assert.Equal(t, common.Idx(255), idx)
+
+	err = db.MakeCheckpoint()
+	require.NoError(t, err)
+
+	idx, err = db.GetCurrentIdx()
+	require.NoError(t, err)
+	assert.Equal(t, common.Idx(255), idx)
+
+	db.Close()
+
+	db, err = NewKVDB(dir, keep)
+	require.NoError(t, err)
+
+	idx, err = db.GetCurrentIdx()
+	require.NoError(t, err)
+	assert.Equal(t, common.Idx(255), idx)
+}
diff --git a/db/statedb/statedb.go b/db/statedb/statedb.go
index 8782ff9..dceb144 100644
--- a/db/statedb/statedb.go
+++ b/db/statedb/statedb.go
@@ -341,6 +341,11 @@ func (s *StateDB) MTGetRoot() *big.Int {
 	return s.MT.Root().BigInt()
 }
 
+// Close the StateDB
+func (s *StateDB) Close() {
+	s.db.Close()
+}
+
 // LocalStateDB represents the local StateDB which allows to make copies from
 // the synchronizer StateDB, and is used by the tx-selector and the
 // batch-builder. LocalStateDB is an in-memory storage.
diff --git a/db/statedb/statedb_test.go b/db/statedb/statedb_test.go
index 22bb45e..da8736f 100644
--- a/db/statedb/statedb_test.go
+++ b/db/statedb/statedb_test.go
@@ -532,3 +532,38 @@ func TestDeleteOldCheckpoints(t *testing.T) {
 		assert.LessOrEqual(t, len(checkpoints), keep)
 	}
 }
+
+func TestCurrentIdx(t *testing.T) {
+	dir, err := ioutil.TempDir("", "tmpdb")
+	require.NoError(t, err)
+	defer require.NoError(t, os.RemoveAll(dir))
+
+	keep := 16
+	sdb, err := NewStateDB(dir, keep, TypeSynchronizer, 32)
+	require.NoError(t, err)
+
+	idx := sdb.CurrentIdx()
+	assert.Equal(t, common.Idx(255), idx)
+
+	sdb.Close()
+
+	sdb, err = NewStateDB(dir, keep, TypeSynchronizer, 32)
+	require.NoError(t, err)
+
+	idx = sdb.CurrentIdx()
+	assert.Equal(t, common.Idx(255), idx)
+
+	err = sdb.MakeCheckpoint()
+	require.NoError(t, err)
+
+	idx = sdb.CurrentIdx()
+	assert.Equal(t, common.Idx(255), idx)
+
+	sdb.Close()
+
+	sdb, err = NewStateDB(dir, keep, TypeSynchronizer, 32)
+	require.NoError(t, err)
+
+	idx = sdb.CurrentIdx()
+	assert.Equal(t, common.Idx(255), idx)
+}