diff --git a/pkg/network/message.go b/pkg/network/message.go
index c61600ac4..1fee8e24f 100644
--- a/pkg/network/message.go
+++ b/pkg/network/message.go
@@ -12,7 +12,7 @@ import (
 	"github.com/nspcc-dev/neo-go/pkg/network/payload"
 )
 
-//go:generate stringer -type=CommandType
+//go:generate stringer -type=CommandType -output=message_string.go
 
 // CompressionMinSize is the lower bound to apply compression.
 const CompressionMinSize = 1024
@@ -68,7 +68,7 @@ const (
 	CMDInv          CommandType = 0x27
 	CMDGetData      CommandType = 0x28
 	CMDGetBlockData CommandType = 0x29
-	CMDUnknown      CommandType = 0x2a
+	CMDNotFound     CommandType = 0x2a
 	CMDTX                       = CommandType(payload.TXType)
 	CMDBlock                    = CommandType(payload.BlockType)
 	CMDConsensus                = CommandType(payload.ConsensusType)
diff --git a/pkg/network/message_string.go b/pkg/network/message_string.go
index 174bdfb53..d505f9696 100644
--- a/pkg/network/message_string.go
+++ b/pkg/network/message_string.go
@@ -1,4 +1,4 @@
-// Code generated by "stringer -type=CommandType"; DO NOT EDIT.
+// Code generated by "stringer -type=CommandType -output=message_string.go"; DO NOT EDIT.
 
 package network
 
@@ -21,7 +21,7 @@ func _() {
 	_ = x[CMDInv-39]
 	_ = x[CMDGetData-40]
 	_ = x[CMDGetBlockData-41]
-	_ = x[CMDUnknown-42]
+	_ = x[CMDNotFound-42]
 	_ = x[CMDTX-43]
 	_ = x[CMDBlock-44]
 	_ = x[CMDConsensus-45]
@@ -39,7 +39,7 @@ const (
 	_CommandType_name_2 = "CMDPingCMDPong"
 	_CommandType_name_3 = "CMDGetHeadersCMDHeaders"
 	_CommandType_name_4 = "CMDGetBlocksCMDMempool"
-	_CommandType_name_5 = "CMDInvCMDGetDataCMDGetBlockDataCMDUnknownCMDTXCMDBlockCMDConsensus"
+	_CommandType_name_5 = "CMDInvCMDGetDataCMDGetBlockDataCMDNotFoundCMDTXCMDBlockCMDConsensus"
 	_CommandType_name_6 = "CMDRejectCMDFilterLoadCMDFilterAddCMDFilterClear"
 	_CommandType_name_7 = "CMDMerkleBlock"
 	_CommandType_name_8 = "CMDAlert"
@@ -51,7 +51,7 @@ var (
 	_CommandType_index_2 = [...]uint8{0, 7, 14}
 	_CommandType_index_3 = [...]uint8{0, 13, 23}
 	_CommandType_index_4 = [...]uint8{0, 12, 22}
-	_CommandType_index_5 = [...]uint8{0, 6, 16, 31, 41, 46, 54, 66}
+	_CommandType_index_5 = [...]uint8{0, 6, 16, 31, 42, 47, 55, 67}
 	_CommandType_index_6 = [...]uint8{0, 9, 22, 34, 48}
 )
 
diff --git a/pkg/network/payload/inventory.go b/pkg/network/payload/inventory.go
index 00e211df6..988c40eb0 100644
--- a/pkg/network/payload/inventory.go
+++ b/pkg/network/payload/inventory.go
@@ -57,7 +57,7 @@ func NewInventory(typ InventoryType, hashes []util.Uint256) *Inventory {
 // DecodeBinary implements Serializable interface.
 func (p *Inventory) DecodeBinary(br *io.BinReader) {
 	p.Type = InventoryType(br.ReadB())
-	br.ReadArray(&p.Hashes)
+	br.ReadArray(&p.Hashes, MaxHashesCount)
 }
 
 // EncodeBinary implements Serializable interface.
diff --git a/pkg/network/server.go b/pkg/network/server.go
index eba1be5cd..90d6858a4 100644
--- a/pkg/network/server.go
+++ b/pkg/network/server.go
@@ -538,6 +538,7 @@ func (s *Server) handleMempoolCmd(p Peer) error {
 
 // handleInvCmd processes the received inventory.
 func (s *Server) handleGetDataCmd(p Peer, inv *payload.Inventory) error {
+	var notFound []util.Uint256
 	for _, hash := range inv.Hashes {
 		var msg *Message
 
@@ -546,11 +547,15 @@ func (s *Server) handleGetDataCmd(p Peer, inv *payload.Inventory) error {
 			tx, _, err := s.chain.GetTransaction(hash)
 			if err == nil {
 				msg = NewMessage(CMDTX, tx)
+			} else {
+				notFound = append(notFound, hash)
 			}
 		case payload.BlockType:
 			b, err := s.chain.GetBlock(hash)
 			if err == nil {
 				msg = NewMessage(CMDBlock, b)
+			} else {
+				notFound = append(notFound, hash)
 			}
 		case payload.ConsensusType:
 			if cp := s.consensus.GetPayload(hash); cp != nil {
@@ -571,6 +576,9 @@ func (s *Server) handleGetDataCmd(p Peer, inv *payload.Inventory) error {
 			}
 		}
 	}
+	if len(notFound) != 0 {
+		return p.EnqueueP2PMessage(NewMessage(CMDNotFound, payload.NewInventory(inv.Type, notFound)))
+	}
 	return nil
 }