diff --git a/weed/s3api/s3api_object_handlers.go b/weed/s3api/s3api_object_handlers.go
index 93d6db79f..fa628f44e 100644
--- a/weed/s3api/s3api_object_handlers.go
+++ b/weed/s3api/s3api_object_handlers.go
@@ -5,12 +5,13 @@ import (
 	"encoding/json"
 	"encoding/xml"
 	"fmt"
-	"github.com/chrislusf/seaweedfs/weed/s3api/s3err"
 	"io"
 	"io/ioutil"
 	"net/http"
 	"strings"
 
+	"github.com/chrislusf/seaweedfs/weed/s3api/s3err"
+
 	"github.com/gorilla/mux"
 
 	"github.com/chrislusf/seaweedfs/weed/glog"
@@ -333,7 +334,7 @@ func (s3a *S3ApiServer) putToFiler(r *http.Request, uploadUrl string, dataReader
 	}
 	if ret.Error != "" {
 		glog.Errorf("upload to filer error: %v", ret.Error)
-		return "", s3err.ErrInternalError
+		return "", filerErrorToS3Error(ret.Error)
 	}
 
 	return etag, s3err.ErrNone
@@ -359,3 +360,10 @@ func getBucketAndObject(r *http.Request) (bucket, object string) {
 
 	return
 }
+
+func filerErrorToS3Error(errString string) s3err.ErrorCode {
+	if strings.HasPrefix(errString, "existing ") && strings.HasSuffix(errString, "is a directory") {
+		return s3err.ErrExistingObjectIsDirectory
+	}
+	return s3err.ErrInternalError
+}
diff --git a/weed/s3api/s3err/s3api_errors.go b/weed/s3api/s3err/s3api_errors.go
index f95652afb..a3f7bb25e 100644
--- a/weed/s3api/s3err/s3api_errors.go
+++ b/weed/s3api/s3err/s3api_errors.go
@@ -92,6 +92,8 @@ const (
 	ErrMissingDateHeader
 	ErrInvalidRequest
 	ErrNotImplemented
+
+	ErrExistingObjectIsDirectory
 )
 
 // error code to APIError structure, these fields carry respective
@@ -344,6 +346,11 @@ var errorCodeResponse = map[ErrorCode]APIError{
 		Description:    "A header you provided implies functionality that is not implemented",
 		HTTPStatusCode: http.StatusNotImplemented,
 	},
+	ErrExistingObjectIsDirectory: {
+		Code:           "ExistingObjectIsDirectory",
+		Description:    "Existing Object is a directory.",
+		HTTPStatusCode: http.StatusConflict,
+	},
 }
 
 // GetAPIError provides API Error for input API error code.