diff --git a/kv/raftstore/meta/keys.go b/kv/raftstore/meta/keys.go
index 8d311adaf..62b619603 100644
--- a/kv/raftstore/meta/keys.go
+++ b/kv/raftstore/meta/keys.go
@@ -88,10 +88,10 @@ func IsRaftStateKey(key []byte) bool {
 
 func DecodeRegionMetaKey(key []byte) (uint64, byte, error) {
 	if len(RegionMetaMinKey)+8+1 != len(key) {
-		return 0, 0, errors.Errorf("invalid region meta key length for key %v", key)
+		return 0, 0, errors.Errorf("invalid region meta key length for key %s", key)
 	}
 	if !bytes.HasPrefix(key, RegionMetaMinKey) {
-		return 0, 0, errors.Errorf("invalid region meta key prefix for key %v", key)
+		return 0, 0, errors.Errorf("invalid region meta key prefix for key %s", key)
 	}
 	regionID := binary.BigEndian.Uint64(key[len(RegionMetaMinKey):])
 	return regionID, key[len(key)-1], nil
@@ -117,7 +117,7 @@ func RegionStateKey(regionID uint64) []byte {
 /// RaftLogIndex gets the log index from raft log key generated by `raft_log_key`.
 func RaftLogIndex(key []byte) (uint64, error) {
 	if len(key) != RegionRaftLogLen {
-		return 0, errors.Errorf("key %v is not a valid raft log key", key)
+		return 0, errors.Errorf("key %s is not a valid raft log key", key)
 	}
 	return binary.BigEndian.Uint64(key[RegionRaftLogLen-8:]), nil
 }
diff --git a/kv/raftstore/runner/region_task.go b/kv/raftstore/runner/region_task.go
index 8b7e5fb64..950514a78 100644
--- a/kv/raftstore/runner/region_task.go
+++ b/kv/raftstore/runner/region_task.go
@@ -1,7 +1,6 @@
 package runner
 
 import (
-	"encoding/hex"
 	"fmt"
 	"time"
 
@@ -132,10 +131,10 @@ func (snapCtx *snapContext) handleApply(regionId uint64, notifier chan<- bool, s
 func (snapCtx *snapContext) cleanUpRange(regionId uint64, startKey, endKey []byte) {
 	if err := engine_util.DeleteRange(snapCtx.engines.Kv, startKey, endKey); err != nil {
 		log.Fatalf("failed to delete data in range, [regionId: %d, startKey: %s, endKey: %s, err: %v]", regionId,
-			hex.EncodeToString(startKey), hex.EncodeToString(endKey), err)
+			startKey, endKey, err)
 	} else {
 		log.Infof("succeed in deleting data in range. [regionId: %d, startKey: %s, endKey: %s]", regionId,
-			hex.EncodeToString(startKey), hex.EncodeToString(endKey))
+			startKey, endKey)
 	}
 }
 
diff --git a/kv/raftstore/runner/split_checker.go b/kv/raftstore/runner/split_checker.go
index 72a2ed369..f023b316a 100644
--- a/kv/raftstore/runner/split_checker.go
+++ b/kv/raftstore/runner/split_checker.go
@@ -1,8 +1,6 @@
 package runner
 
 import (
-	"encoding/hex"
-
 	"github.com/Connor1996/badger"
 	"github.com/pingcap-incubator/tinykv/kv/config"
 	"github.com/pingcap-incubator/tinykv/kv/raftstore/message"
@@ -43,7 +41,7 @@ func (r *splitCheckHandler) Handle(t worker.Task) {
 	region := spCheckTask.Region
 	regionId := region.Id
 	log.Debugf("executing split check worker.Task: [regionId: %d, startKey: %s, endKey: %s]", regionId,
-		hex.EncodeToString(region.StartKey), hex.EncodeToString(region.EndKey))
+		region.StartKey, region.EndKey)
 	key := r.splitCheck(regionId, region.StartKey, region.EndKey)
 	if key != nil {
 		_, userKey, err := codec.DecodeBytes(key)
diff --git a/kv/raftstore/util/error.go b/kv/raftstore/util/error.go
index 0f54d63d1..5843ad06f 100644
--- a/kv/raftstore/util/error.go
+++ b/kv/raftstore/util/error.go
@@ -31,7 +31,7 @@ type ErrKeyNotInRegion struct {
 }
 
 func (e *ErrKeyNotInRegion) Error() string {
-	return fmt.Sprintf("key %v is not in region %v", e.Key, e.Region)
+	return fmt.Sprintf("key %s is not in region %v", e.Key, e.Region)
 }
 
 type ErrEpochNotMatch struct {
diff --git a/kv/test_raftstore/cluster.go b/kv/test_raftstore/cluster.go
index 11de7afd5..f3ca9fea4 100644
--- a/kv/test_raftstore/cluster.go
+++ b/kv/test_raftstore/cluster.go
@@ -3,7 +3,6 @@ package test_raftstore
 import (
 	"bytes"
 	"context"
-	"encoding/hex"
 	"fmt"
 	"io/ioutil"
 	"math/rand"
@@ -274,7 +273,7 @@ func (c *Cluster) GetRegion(key []byte) *metapb.Region {
 		// retry to get the region again.
 		SleepMS(20)
 	}
-	panic(fmt.Sprintf("find no region for %s", hex.EncodeToString(key)))
+	panic(fmt.Sprintf("find no region for %s", key))
 }
 
 func (c *Cluster) GetRandomRegion() *metapb.Region {
diff --git a/kv/test_raftstore/utils.go b/kv/test_raftstore/utils.go
index dc4ac9534..b8abdc8b6 100644
--- a/kv/test_raftstore/utils.go
+++ b/kv/test_raftstore/utils.go
@@ -2,7 +2,6 @@ package test_raftstore
 
 import (
 	"bytes"
-	"encoding/hex"
 	"fmt"
 	"time"
 
@@ -100,7 +99,7 @@ func MustGetCf(engine *engine_util.Engines, cf string, key []byte, value []byte)
 		}
 		SleepMS(20)
 	}
-	panic(fmt.Sprintf("can't get value %s for key %s", hex.EncodeToString(value), hex.EncodeToString(key)))
+	panic(fmt.Sprintf("can't get value %s for key %s", value, key))
 }
 
 func MustGetCfEqual(engine *engine_util.Engines, cf string, key []byte, value []byte) {
@@ -121,7 +120,7 @@ func MustGetCfNone(engine *engine_util.Engines, cf string, key []byte) {
 		}
 		SleepMS(20)
 	}
-	panic(fmt.Sprintf("get value %s for key %s", hex.EncodeToString(val), hex.EncodeToString(key)))
+	panic(fmt.Sprintf("get value %s for key %s", val, key))
 }
 
 func MustGetNone(engine *engine_util.Engines, key []byte) {