diff --git a/blockpool/peers.go b/blockpool/peers.go
index 615058e267..285fa45b13 100644
--- a/blockpool/peers.go
+++ b/blockpool/peers.go
@@ -133,13 +133,10 @@ func (self *peer) addError(code int, format string, params ...interface{}) {
 	self.addToBlacklist(self.id)
 }
 
+// caller must hold peer lock
 func (self *peer) setChainInfo(td *big.Int, c common.Hash) {
-	self.lock.Lock()
-	defer self.lock.Unlock()
-
 	self.td = td
 	self.currentBlockHash = c
-
 	self.currentBlock = nil
 	self.parentHash = common.Hash{}
 	self.headSection = nil
@@ -171,7 +168,7 @@ func (self *peers) requestBlocks(attempts int, hashes []common.Hash) {
 	defer self.lock.RUnlock()
 	peerCount := len(self.peers)
 	// on first attempt use the best peer
-	if attempts == 0 {
+	if attempts == 0 && self.best != nil {
 		plog.DebugDetailf("request %v missing blocks from best peer <%s>", len(hashes), self.best.id)
 		self.best.requestBlocks(hashes)
 		return
@@ -219,10 +216,12 @@ func (self *peers) addPeer(
 		return
 	}
 	self.lock.Lock()
+	defer self.lock.Unlock()
 	p, found := self.peers[id]
 	if found {
 		// when called on an already connected peer, it means a newBlockMsg is received
 		// peer head info is updated
+		p.lock.Lock()
 		if p.currentBlockHash != currentBlockHash {
 			previousBlockHash = p.currentBlockHash
 			plog.Debugf("addPeer: Update peer <%s> with td %v and current block %s (was %v)", id, td, hex(currentBlockHash), hex(previousBlockHash))
@@ -232,6 +231,7 @@ func (self *peers) addPeer(
 			self.status.values.NewBlocks++
 			self.status.lock.Unlock()
 		}
+		p.lock.Unlock()
 	} else {
 		p = self.newPeer(td, currentBlockHash, id, requestBlockHashes, requestBlocks, peerError)
 
@@ -243,7 +243,6 @@ func (self *peers) addPeer(
 
 		plog.Debugf("addPeer: add new peer <%v> with td %v and current block %s", id, td, hex(currentBlockHash))
 	}
-	self.lock.Unlock()
 
 	// check if peer's current head block is known
 	if self.bp.hasBlock(currentBlockHash) {
@@ -269,7 +268,10 @@ func (self *peers) addPeer(
 	} else {
 		// baseline is our own TD
 		currentTD := self.bp.getTD()
-		if self.best != nil {
+		bestpeer := self.best
+		if bestpeer != nil {
+			bestpeer.lock.Lock()
+			defer bestpeer.lock.Unlock()
 			currentTD = self.best.td
 		}
 		if td.Cmp(currentTD) > 0 {
@@ -277,11 +279,12 @@ func (self *peers) addPeer(
 			self.status.bestPeers[p.id]++
 			self.status.lock.Unlock()
 			plog.Debugf("addPeer: peer <%v> (td: %v > current td %v) promoted best peer", id, td, currentTD)
-			self.bp.switchPeer(self.best, p)
+			self.bp.switchPeer(bestpeer, p)
 			self.best = p
 			best = true
 		}
 	}
+
 	return
 }
 
diff --git a/common/bytes.go b/common/bytes.go
index 2d885ac746..5bdacd810a 100644
--- a/common/bytes.go
+++ b/common/bytes.go
@@ -127,6 +127,11 @@ func CopyBytes(b []byte) (copiedBytes []byte) {
 	return
 }
 
+func HasHexPrefix(str string) bool {
+	l := len(str)
+	return l >= 2 && str[0:2] == "0x"
+}
+
 func IsHex(str string) bool {
 	l := len(str)
 	return l >= 4 && l%2 == 0 && str[0:2] == "0x"
diff --git a/core/block_processor.go b/core/block_processor.go
index 97c8855361..0a98f3e32e 100644
--- a/core/block_processor.go
+++ b/core/block_processor.go
@@ -342,7 +342,7 @@ func (sm *BlockProcessor) VerifyUncles(statedb *state.StateDB, block, parent *ty
 			return UncleError(fmt.Sprintf("Uncle's parent unknown (%x)", uncle.ParentHash[0:4]))
 		}
 
-		if err := sm.ValidateHeader(uncle, ancestorHeaders[uncle.ParentHash]); err != nil && err != BlockEqualTSErr {
+		if err := sm.ValidateHeader(uncle, ancestorHeaders[uncle.ParentHash]); err != nil {
 			return ValidationError(fmt.Sprintf("%v", err))
 		}
 
diff --git a/core/chain_manager.go b/core/chain_manager.go
index d97a94b062..bf5ba9b405 100644
--- a/core/chain_manager.go
+++ b/core/chain_manager.go
@@ -448,7 +448,8 @@ func (self *ChainManager) InsertChain(chain types.Blocks) error {
 			}
 
 			if err == BlockEqualTSErr {
-				queue[i] = ChainSideEvent{block, logs}
+				//queue[i] = ChainSideEvent{block, logs}
+				// XXX silently discard it?
 				continue
 			}
 
diff --git a/rpc/api.go b/rpc/api.go
index afd242aa3d..30ba1ddc1d 100644
--- a/rpc/api.go
+++ b/rpc/api.go
@@ -2,6 +2,7 @@ package rpc
 
 import (
 	"encoding/json"
+	// "fmt"
 	"math/big"
 	"sync"
 
@@ -112,7 +113,11 @@ func (api *EthereumApi) GetRequestReply(req *RpcRequest, reply *interface{}) err
 		}
 
 		block := NewBlockRes(api.xeth().EthBlockByHash(args.Hash), false)
-		*reply = common.ToHex(big.NewInt(int64(len(block.Transactions))).Bytes())
+		if block == nil {
+			*reply = nil
+		} else {
+			*reply = common.ToHex(big.NewInt(int64(len(block.Transactions))).Bytes())
+		}
 	case "eth_getBlockTransactionCountByNumber":
 		args := new(BlockNumArg)
 		if err := json.Unmarshal(req.Params, &args); err != nil {
@@ -192,9 +197,9 @@ func (api *EthereumApi) GetRequestReply(req *RpcRequest, reply *interface{}) err
 
 		*reply = br
 	case "eth_getTransactionByHash":
-		// HashIndexArgs used, but only the "Hash" part we need.
-		args := new(HashIndexArgs)
+		args := new(HashArgs)
 		if err := json.Unmarshal(req.Params, &args); err != nil {
+			return err
 		}
 		tx, bhash, bnum, txi := api.xeth().EthTransactionByHash(args.Hash)
 		if tx != nil {
@@ -212,11 +217,16 @@ func (api *EthereumApi) GetRequestReply(req *RpcRequest, reply *interface{}) err
 
 		block := api.xeth().EthBlockByHash(args.Hash)
 		br := NewBlockRes(block, true)
+		if br == nil {
+			*reply = nil
+		}
 
 		if args.Index >= int64(len(br.Transactions)) || args.Index < 0 {
-			return NewValidationError("Index", "does not exist")
+			// return NewValidationError("Index", "does not exist")
+			*reply = nil
+		} else {
+			*reply = br.Transactions[args.Index]
 		}
-		*reply = br.Transactions[args.Index]
 	case "eth_getTransactionByBlockNumberAndIndex":
 		args := new(BlockNumIndexArgs)
 		if err := json.Unmarshal(req.Params, &args); err != nil {
@@ -225,11 +235,16 @@ func (api *EthereumApi) GetRequestReply(req *RpcRequest, reply *interface{}) err
 
 		block := api.xeth().EthBlockByNumber(args.BlockNumber)
 		v := NewBlockRes(block, true)
+		if v == nil {
+			*reply = nil
+		}
 
 		if args.Index >= int64(len(v.Transactions)) || args.Index < 0 {
-			return NewValidationError("Index", "does not exist")
+			// return NewValidationError("Index", "does not exist")
+			*reply = nil
+		} else {
+			*reply = v.Transactions[args.Index]
 		}
-		*reply = v.Transactions[args.Index]
 	case "eth_getUncleByBlockHashAndIndex":
 		args := new(HashIndexArgs)
 		if err := json.Unmarshal(req.Params, &args); err != nil {
@@ -243,13 +258,11 @@ func (api *EthereumApi) GetRequestReply(req *RpcRequest, reply *interface{}) err
 		}
 
 		if args.Index >= int64(len(br.Uncles)) || args.Index < 0 {
-			return NewValidationError("Index", "does not exist")
+			// return NewValidationError("Index", "does not exist")
+			*reply = nil
+		} else {
+			*reply = br.Uncles[args.Index]
 		}
-
-		uhash := br.Uncles[args.Index]
-		uncle := NewBlockRes(api.xeth().EthBlockByHash(uhash.String()), false)
-
-		*reply = uncle
 	case "eth_getUncleByBlockNumberAndIndex":
 		args := new(BlockNumIndexArgs)
 		if err := json.Unmarshal(req.Params, &args); err != nil {
@@ -265,13 +278,11 @@ func (api *EthereumApi) GetRequestReply(req *RpcRequest, reply *interface{}) err
 		}
 
 		if args.Index >= int64(len(v.Uncles)) || args.Index < 0 {
-			return NewValidationError("Index", "does not exist")
+			// return NewValidationError("Index", "does not exist")
+			*reply = nil
+		} else {
+			*reply = v.Uncles[args.Index]
 		}
-
-		uhash := v.Uncles[args.Index]
-		uncle := NewBlockRes(api.xeth().EthBlockByHash(uhash.String()), false)
-
-		*reply = uncle
 	case "eth_getCompilers":
 		c := []string{""}
 		*reply = c
diff --git a/rpc/args.go b/rpc/args.go
index 70618a01a4..cebabf4ba9 100644
--- a/rpc/args.go
+++ b/rpc/args.go
@@ -41,7 +41,11 @@ func blockHeight(raw interface{}, number *int64) error {
 	case "pending":
 		*number = -2
 	default:
-		*number = common.String2Big(str).Int64()
+		if common.HasHexPrefix(str) {
+			*number = common.String2Big(str).Int64()
+		} else {
+			return NewInvalidTypeError("blockNumber", "is not a valid string")
+		}
 	}
 
 	return nil
@@ -1021,12 +1025,15 @@ func (args *WhisperFilterArgs) UnmarshalJSON(b []byte) (err error) {
 		return NewInsufficientParamsError(len(obj), 1)
 	}
 
-	var argstr string
-	argstr, ok := obj[0].To.(string)
-	if !ok {
-		return NewInvalidTypeError("to", "is not a string")
+	if obj[0].To == nil {
+		args.To = ""
+	} else {
+		argstr, ok := obj[0].To.(string)
+		if !ok {
+			return NewInvalidTypeError("to", "is not a string")
+		}
+		args.To = argstr
 	}
-	args.To = argstr
 
 	t := make([]string, len(obj[0].Topics))
 	for i, j := range obj[0].Topics {
diff --git a/rpc/args_test.go b/rpc/args_test.go
index 902f8013e4..b88bab2805 100644
--- a/rpc/args_test.go
+++ b/rpc/args_test.go
@@ -1805,6 +1805,16 @@ func TestWhisperFilterArgsEmpty(t *testing.T) {
 	}
 }
 
+func TestWhisperFilterArgsToInt(t *testing.T) {
+	input := `[{"to": 2}]`
+
+	args := new(WhisperFilterArgs)
+	str := ExpectInvalidTypeError(json.Unmarshal([]byte(input), args))
+	if len(str) > 0 {
+		t.Error(str)
+	}
+}
+
 func TestWhisperFilterArgsToBool(t *testing.T) {
 	input := `[{"topics": ["0x68656c6c6f20776f726c64"], "to": false}]`
 
@@ -1815,6 +1825,21 @@ func TestWhisperFilterArgsToBool(t *testing.T) {
 	}
 }
 
+func TestWhisperFilterArgsToMissing(t *testing.T) {
+	input := `[{"topics": ["0x68656c6c6f20776f726c64"]}]`
+	expected := new(WhisperFilterArgs)
+	expected.To = ""
+
+	args := new(WhisperFilterArgs)
+	if err := json.Unmarshal([]byte(input), &args); err != nil {
+		t.Error(err)
+	}
+
+	if args.To != expected.To {
+		t.Errorf("To shoud be %v but is %v", expected.To, args.To)
+	}
+}
+
 func TestWhisperFilterArgsTopicInt(t *testing.T) {
 	input := `[{"topics": [6], "to": "0x34ag445g3455b34"}]`
 
@@ -2090,6 +2115,51 @@ func TestHashIndexArgsInvalidIndex(t *testing.T) {
 	}
 }
 
+func TestHashArgs(t *testing.T) {
+	input := `["0xc6ef2fc5426d6ad6fd9e2a26abeab0aa2411b7ab17f30a99d3cb96aed1d1055b"]`
+	expected := new(HashIndexArgs)
+	expected.Hash = "0xc6ef2fc5426d6ad6fd9e2a26abeab0aa2411b7ab17f30a99d3cb96aed1d1055b"
+
+	args := new(HashArgs)
+	if err := json.Unmarshal([]byte(input), &args); err != nil {
+		t.Error(err)
+	}
+
+	if expected.Hash != args.Hash {
+		t.Errorf("Hash shoud be %#v but is %#v", expected.Hash, args.Hash)
+	}
+}
+
+func TestHashArgsEmpty(t *testing.T) {
+	input := `[]`
+
+	args := new(HashArgs)
+	str := ExpectInsufficientParamsError(json.Unmarshal([]byte(input), &args))
+	if len(str) > 0 {
+		t.Error(str)
+	}
+}
+
+func TestHashArgsInvalid(t *testing.T) {
+	input := `{}`
+
+	args := new(HashArgs)
+	str := ExpectDecodeParamError(json.Unmarshal([]byte(input), &args))
+	if len(str) > 0 {
+		t.Error(str)
+	}
+}
+
+func TestHashArgsInvalidHash(t *testing.T) {
+	input := `[7]`
+
+	args := new(HashArgs)
+	str := ExpectInvalidTypeError(json.Unmarshal([]byte(input), &args))
+	if len(str) > 0 {
+		t.Error(str)
+	}
+}
+
 func TestSubmitWorkArgs(t *testing.T) {
 	input := `["0x0000000000000001", "0x1234567890abcdef1234567890abcdef", "0xD1GE5700000000000000000000000000"]`
 	expected := new(SubmitWorkArgs)
diff --git a/rpc/responses.go b/rpc/responses.go
index 3d1687cb68..52a2f714c1 100644
--- a/rpc/responses.go
+++ b/rpc/responses.go
@@ -28,7 +28,7 @@ type BlockRes struct {
 	GasUsed         *hexnum           `json:"gasUsed"`
 	UnixTimestamp   *hexnum           `json:"timestamp"`
 	Transactions    []*TransactionRes `json:"transactions"`
-	Uncles          []*hexdata        `json:"uncles"`
+	Uncles          []*UncleRes       `json:"uncles"`
 }
 
 func (b *BlockRes) MarshalJSON() ([]byte, error) {
@@ -73,7 +73,10 @@ func (b *BlockRes) MarshalJSON() ([]byte, error) {
 		ext.GasUsed = b.GasUsed
 		ext.UnixTimestamp = b.UnixTimestamp
 		ext.Transactions = b.Transactions
-		ext.Uncles = b.Uncles
+		ext.Uncles = make([]*hexdata, len(b.Uncles))
+		for i, u := range b.Uncles {
+			ext.Uncles[i] = u.BlockHash
+		}
 		return json.Marshal(ext)
 	} else {
 		var ext struct {
@@ -119,14 +122,15 @@ func (b *BlockRes) MarshalJSON() ([]byte, error) {
 		for i, tx := range b.Transactions {
 			ext.Transactions[i] = tx.Hash
 		}
-		ext.Uncles = b.Uncles
+		ext.Uncles = make([]*hexdata, len(b.Uncles))
+		for i, u := range b.Uncles {
+			ext.Uncles[i] = u.BlockHash
+		}
 		return json.Marshal(ext)
 	}
 }
 
 func NewBlockRes(block *types.Block, fullTx bool) *BlockRes {
-	// TODO respect fullTx flag
-
 	if block == nil {
 		return nil
 	}
@@ -159,9 +163,9 @@ func NewBlockRes(block *types.Block, fullTx bool) *BlockRes {
 		res.Transactions[i].TxIndex = newHexNum(i)
 	}
 
-	res.Uncles = make([]*hexdata, len(block.Uncles()))
+	res.Uncles = make([]*UncleRes, len(block.Uncles()))
 	for i, uncle := range block.Uncles() {
-		res.Uncles[i] = newHexData(uncle.Hash())
+		res.Uncles[i] = NewUncleRes(uncle)
 	}
 
 	return res
@@ -182,6 +186,10 @@ type TransactionRes struct {
 }
 
 func NewTransactionRes(tx *types.Transaction) *TransactionRes {
+	if tx == nil {
+		return nil
+	}
+
 	var v = new(TransactionRes)
 	v.Hash = newHexData(tx.Hash())
 	v.Nonce = newHexNum(tx.Nonce())
@@ -198,6 +206,49 @@ func NewTransactionRes(tx *types.Transaction) *TransactionRes {
 	return v
 }
 
+type UncleRes struct {
+	BlockNumber     *hexnum  `json:"number"`
+	BlockHash       *hexdata `json:"hash"`
+	ParentHash      *hexdata `json:"parentHash"`
+	Nonce           *hexdata `json:"nonce"`
+	Sha3Uncles      *hexdata `json:"sha3Uncles"`
+	ReceiptHash     *hexdata `json:"receiptHash"`
+	LogsBloom       *hexdata `json:"logsBloom"`
+	TransactionRoot *hexdata `json:"transactionsRoot"`
+	StateRoot       *hexdata `json:"stateRoot"`
+	Miner           *hexdata `json:"miner"`
+	Difficulty      *hexnum  `json:"difficulty"`
+	ExtraData       *hexdata `json:"extraData"`
+	GasLimit        *hexnum  `json:"gasLimit"`
+	GasUsed         *hexnum  `json:"gasUsed"`
+	UnixTimestamp   *hexnum  `json:"timestamp"`
+}
+
+func NewUncleRes(h *types.Header) *UncleRes {
+	if h == nil {
+		return nil
+	}
+
+	var v = new(UncleRes)
+	v.BlockNumber = newHexNum(h.Number)
+	v.BlockHash = newHexData(h.Hash())
+	v.ParentHash = newHexData(h.ParentHash)
+	v.Sha3Uncles = newHexData(h.UncleHash)
+	v.Nonce = newHexData(h.Nonce[:])
+	v.LogsBloom = newHexData(h.Bloom)
+	v.TransactionRoot = newHexData(h.TxHash)
+	v.StateRoot = newHexData(h.Root)
+	v.Miner = newHexData(h.Coinbase)
+	v.Difficulty = newHexNum(h.Difficulty)
+	v.ExtraData = newHexData(h.Extra)
+	v.GasLimit = newHexNum(h.GasLimit)
+	v.GasUsed = newHexNum(h.GasUsed)
+	v.UnixTimestamp = newHexNum(h.Time)
+	v.ReceiptHash = newHexData(h.ReceiptHash)
+
+	return v
+}
+
 // type FilterLogRes struct {
 // 	Hash             string `json:"hash"`
 // 	Address          string `json:"address"`
diff --git a/xeth/xeth.go b/xeth/xeth.go
index b203e45dee..825f26017c 100644
--- a/xeth/xeth.go
+++ b/xeth/xeth.go
@@ -196,7 +196,7 @@ func (self *XEth) EthTransactionByHash(hash string) (tx *types.Transaction, blha
 	// meta
 	var txExtra struct {
 		BlockHash  common.Hash
-		BlockIndex int64
+		BlockIndex uint64
 		Index      uint64
 	}
 
@@ -205,8 +205,10 @@ func (self *XEth) EthTransactionByHash(hash string) (tx *types.Transaction, blha
 	err := rlp.Decode(r, &txExtra)
 	if err == nil {
 		blhash = txExtra.BlockHash
-		blnum = big.NewInt(txExtra.BlockIndex)
+		blnum = big.NewInt(int64(txExtra.BlockIndex))
 		txi = txExtra.Index
+	} else {
+		pipelogger.Errorln(err)
 	}
 
 	return