diff --git a/pkg/core/blockchain.go b/pkg/core/blockchain.go
index 7bf69325e..1d4c6de18 100644
--- a/pkg/core/blockchain.go
+++ b/pkg/core/blockchain.go
@@ -396,8 +396,12 @@ func (bc *Blockchain) notificationDispatcher() {
 // Close stops Blockchain's internal loop, syncs changes to persistent storage
 // and closes it. The Blockchain is no longer functional after the call to Close.
 func (bc *Blockchain) Close() {
+	// If there is a block addition in progress, wait for it to finish and
+	// don't allow new ones.
+	bc.addLock.Lock()
 	close(bc.stopCh)
 	<-bc.runToExitCh
+	bc.addLock.Unlock()
 }
 
 // AddBlock accepts successive block for the Blockchain, verifies it and
diff --git a/pkg/core/helper_test.go b/pkg/core/helper_test.go
index c4ff4f4b6..a334baa33 100644
--- a/pkg/core/helper_test.go
+++ b/pkg/core/helper_test.go
@@ -234,7 +234,7 @@ func TestCreateBasicChain(t *testing.T) {
 	}
 	m.ABI.EntryPoint.ReturnType = smartcontract.BoolType
 	m.Features = smartcontract.HasStorage
-	bs, err := testserdes.EncodeBinary(m)
+	bs, err := m.MarshalJSON()
 	require.NoError(t, err)
 	emit.Bytes(script.BinWriter, bs)
 	emit.Bytes(script.BinWriter, avm)
diff --git a/pkg/core/interop_neo.go b/pkg/core/interop_neo.go
index e27919ae5..6717c620c 100644
--- a/pkg/core/interop_neo.go
+++ b/pkg/core/interop_neo.go
@@ -8,7 +8,6 @@ import (
 
 	"github.com/nspcc-dev/neo-go/pkg/core/interop"
 	"github.com/nspcc-dev/neo-go/pkg/core/state"
-	"github.com/nspcc-dev/neo-go/pkg/io"
 	"github.com/nspcc-dev/neo-go/pkg/smartcontract/manifest"
 	"github.com/nspcc-dev/neo-go/pkg/util"
 	"github.com/nspcc-dev/neo-go/pkg/vm"
@@ -76,10 +75,9 @@ func createContractStateFromVM(ic *interop.Context, v *vm.VM) (*state.Contract,
 		return nil, errGasLimitExceeded
 	}
 	var m manifest.Manifest
-	r := io.NewBinReaderFromBuf(manifestBytes)
-	m.DecodeBinary(r)
-	if r.Err != nil {
-		return nil, r.Err
+	err := m.UnmarshalJSON(manifestBytes)
+	if err != nil {
+		return nil, err
 	}
 	return &state.Contract{
 		Script:   script,
diff --git a/pkg/core/native/native_gas.go b/pkg/core/native/native_gas.go
index 4d76ceac7..2e1e57ada 100644
--- a/pkg/core/native/native_gas.go
+++ b/pkg/core/native/native_gas.go
@@ -80,6 +80,9 @@ func (g *GAS) Initialize(ic *interop.Context) error {
 
 // OnPersist implements Contract interface.
 func (g *GAS) OnPersist(ic *interop.Context) error {
+	if len(ic.Block.Transactions) == 0 {
+		return nil
+	}
 	for _, tx := range ic.Block.Transactions {
 		absAmount := big.NewInt(int64(tx.SystemFee + tx.NetworkFee))
 		g.burn(ic, tx.Sender, absAmount)
diff --git a/pkg/core/state/native_state.go b/pkg/core/state/native_state.go
index d551c6711..bb1d94ebf 100644
--- a/pkg/core/state/native_state.go
+++ b/pkg/core/state/native_state.go
@@ -125,6 +125,7 @@ func (s *NEOBalanceState) fromStackItem(item stackitem.Item) {
 	votes := structItem[2].Value().([]stackitem.Item)
 	s.Votes = make([]*keys.PublicKey, len(votes))
 	for i, v := range votes {
+		s.Votes[i] = new(keys.PublicKey)
 		s.Votes[i].DecodeBytes(v.Value().([]byte))
 	}
 }
diff --git a/pkg/network/server.go b/pkg/network/server.go
index befc08ef4..2127691dd 100644
--- a/pkg/network/server.go
+++ b/pkg/network/server.go
@@ -648,7 +648,7 @@ func (s *Server) handleTxCmd(tx *transaction.Transaction) error {
 func (s *Server) handleAddrCmd(p Peer, addrs *payload.AddressList) error {
 	for _, a := range addrs.Addrs {
 		addr, err := a.GetTCPAddress()
-		if err != nil {
+		if err == nil {
 			s.discovery.BackFill(addr)
 		}
 	}
diff --git a/pkg/rpc/request/txBuilder.go b/pkg/rpc/request/txBuilder.go
index 7176ff7f2..a28f94d4b 100644
--- a/pkg/rpc/request/txBuilder.go
+++ b/pkg/rpc/request/txBuilder.go
@@ -19,9 +19,10 @@ import (
 // with its metadata and system fee require for this.
 func CreateDeploymentScript(avm []byte, manif *manifest.Manifest) ([]byte, util.Fixed8, error) {
 	script := io.NewBufBinWriter()
-	w := io.NewBufBinWriter()
-	manif.EncodeBinary(w.BinWriter)
-	rawManifest := w.Bytes()
+	rawManifest, err := manif.MarshalJSON()
+	if err != nil {
+		return nil, 0, err
+	}
 	emit.Bytes(script.BinWriter, rawManifest)
 	emit.Bytes(script.BinWriter, avm)
 	emit.Syscall(script.BinWriter, "System.Contract.Create")
diff --git a/pkg/rpc/server/server_test.go b/pkg/rpc/server/server_test.go
index a8428a642..7cd510479 100644
--- a/pkg/rpc/server/server_test.go
+++ b/pkg/rpc/server/server_test.go
@@ -51,7 +51,7 @@ type rpcTestCase struct {
 }
 
 const testContractHash = "e65ff7b3a02d207b584a5c27057d4e9862ef01da"
-const deploymentTxHash = "5ce44eae362d3f81d440cb73cf4e4af71e69851bcd683b076aa08b7346d4e69b"
+const deploymentTxHash = "b0428600383ec7f7b06734978a24dbe81edc87b781f58c0614f122c735d8cf6a"
 
 var rpcTestCases = map[string][]rpcTestCase{
 	"getapplicationlog": {
@@ -148,7 +148,7 @@ var rpcTestCases = map[string][]rpcTestCase{
 						},
 						{
 							Asset:       e.chain.UtilityTokenHash(),
-							Amount:      "923.96934740",
+							Amount:      "923.96937740",
 							LastUpdated: 6,
 						}},
 					Address: testchain.PrivateKeyByID(0).GetScriptHash().StringLE(),
diff --git a/pkg/rpc/server/testdata/testblocks.acc b/pkg/rpc/server/testdata/testblocks.acc
index 2a6c5f910..aa3bb8e87 100644
Binary files a/pkg/rpc/server/testdata/testblocks.acc and b/pkg/rpc/server/testdata/testblocks.acc differ