diff --git a/api/proto/discovery/pingpong_test.go b/api/proto/discovery/pingpong_test.go
index 0257ab4cf..3895190c8 100644
--- a/api/proto/discovery/pingpong_test.go
+++ b/api/proto/discovery/pingpong_test.go
@@ -89,6 +89,9 @@ func TestSerialize(test *testing.T) {
 	buf2 = pong1.ConstructPongMessage()
 
 	msg2, err := proto.GetMessagePayload(buf2)
+	if err != nil {
+		test.Error("GetMessagePayload Failed!")
+	}
 	pong, err := GetPongMessage(msg2)
 	if err != nil {
 		test.Error("Pong failed!")
diff --git a/api/service/explorer/service.go b/api/service/explorer/service.go
index 30b4f597b..ef66e8906 100644
--- a/api/service/explorer/service.go
+++ b/api/service/explorer/service.go
@@ -146,12 +146,19 @@ func (s *Service) GetExplorerBlocks(w http.ResponseWriter, r *http.Request) {
 	}
 	db := s.storage.GetDB()
 	fromInt, err := strconv.Atoi(from)
+	if err != nil {
+		json.NewEncoder(w).Encode(data.Blocks)
+		return
+	}
 	var toInt int
 	if to == "" {
-		bytes, err := db.Get([]byte(BlockHeightKey))
-		if err == nil {
-			toInt, err = strconv.Atoi(string(bytes))
-		}
+		toInt, err = func() (int, error) {
+			bytes, err := db.Get([]byte(BlockHeightKey))
+			if err == nil {
+				return strconv.Atoi(string(bytes))
+			}
+			return toInt, err
+		}()
 	} else {
 		toInt, err = strconv.Atoi(to)
 	}
diff --git a/consensus/consensus_validator_test.go b/consensus/consensus_validator_test.go
index 1a13aa82b..c7b893115 100644
--- a/consensus/consensus_validator_test.go
+++ b/consensus/consensus_validator_test.go
@@ -79,8 +79,14 @@ func TestProcessMessageValidatorAnnounce(test *testing.T) {
 		test.Fatalf("Cannot craeate consensus: %v", err)
 	}
 	blockBytes, err := hex.DecodeString("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")
+	if err != nil {
+		test.Fatalf("Cannot decode blockByte: %v", err)
+	}
 	consensusLeader.block = blockBytes
 	hashBytes, err := hex.DecodeString("bdd66a8211ffcbf0ad431b506c854b49264951fd9f690928e9cf44910c381053")
+	if err != nil {
+		test.Fatalf("Cannot decode hashByte: %v", err)
+	}
 
 	copy(consensusLeader.blockHash[:], hashBytes[:])
 
@@ -140,8 +146,14 @@ func TestProcessMessageValidatorPrepared(test *testing.T) {
 		test.Fatalf("Cannot craeate consensus: %v", err)
 	}
 	blockBytes, err := hex.DecodeString("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")
+	if err != nil {
+		test.Fatalf("Cannot decode blockByte: %v", err)
+	}
 	consensusLeader.block = blockBytes
 	hashBytes, err := hex.DecodeString("bdd66a8211ffcbf0ad431b506c854b49264951fd9f690928e9cf44910c381053")
+	if err != nil {
+		test.Fatalf("Cannot decode hashByte: %v", err)
+	}
 
 	copy(consensusLeader.blockHash[:], hashBytes[:])
 
@@ -216,8 +228,14 @@ func TestProcessMessageValidatorCommitted(test *testing.T) {
 		test.Fatalf("Cannot craeate consensus: %v", err)
 	}
 	blockBytes, err := hex.DecodeString("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")
+	if err != nil {
+		test.Fatalf("Cannot decode blockByte: %v", err)
+	}
 	consensusLeader.block = blockBytes
 	hashBytes, err := hex.DecodeString("bdd66a8211ffcbf0ad431b506c854b49264951fd9f690928e9cf44910c381053")
+	if err != nil {
+		test.Fatalf("Cannot decode hashByte: %v", err)
+	}
 
 	copy(consensusLeader.blockHash[:], hashBytes[:])
 
diff --git a/node/contract.go b/node/contract.go
index 5d6697577..47e1f7176 100644
--- a/node/contract.go
+++ b/node/contract.go
@@ -75,6 +75,11 @@ func (node *Node) QueryStakeInfo() *structs.StakeInfoReturnValue {
 
 	state, err := node.blockchain.State()
 
+	if err != nil {
+		utils.GetLogInstance().Error("Failed to get blockchain state", "error", err)
+		return nil
+	}
+
 	stakingContractAddress := crypto.CreateAddress(deployerAddress, uint64(0))
 	tx := types.NewTransaction(
 		state.GetNonce(deployerAddress),
diff --git a/node/demo_contract.go b/node/demo_contract.go
index 1d28931d1..b1477fdc0 100644
--- a/node/demo_contract.go
+++ b/node/demo_contract.go
@@ -130,6 +130,10 @@ func (node *Node) GetResult(priKey string) (players []string, balances []*big.In
 
 	demoContractAddress := node.DemoContractAddress
 	key, err := crypto.HexToECDSA(priKey)
+	if err != nil {
+		utils.GetLogInstance().Error("Failed to parse private key", "error", err)
+	}
+
 	nonce := node.GetNonceOfAddress(crypto.PubkeyToAddress(key.PublicKey))
 
 	tx := types.NewTransaction(
diff --git a/test/p2pchat/chat.go b/test/p2pchat/chat.go
index 3bfac7c9f..af4680690 100644
--- a/test/p2pchat/chat.go
+++ b/test/p2pchat/chat.go
@@ -136,12 +136,17 @@ func main() {
 	}
 
 	if err != nil {
-		fmt.Printf("pubsub error: %v", err)
+		fmt.Printf("pub error: %v", err)
 		panic(err)
 	}
 
 	sub, err := ps.Subscribe("pubsubtestchannel")
 
+	if err != nil {
+		fmt.Printf("sub error: %v", err)
+		panic(err)
+	}
+
 	go writePubsub(ps)
 	go readPubsub(sub)