diff --git a/tools/count_api_without_core_ops.py b/tools/count_api_without_core_ops.py
index 99e84074158ad7ddbdb91148b53cc3433f03f3f8..664b94a059f5c8adbe541615e5472b43ad256915 100644
--- a/tools/count_api_without_core_ops.py
+++ b/tools/count_api_without_core_ops.py
@@ -22,6 +22,7 @@ import pydoc
 import hashlib
 import six
 import functools
+import platform
 
 __all__ = ['get_apis_with_and_without_core_ops', ]
 
@@ -34,9 +35,20 @@ omitted_list = [
 
 
 def md5(doc):
-    hash = hashlib.md5()
-    hash.update(str(doc).encode('utf-8'))
-    return hash.hexdigest()
+    try:
+        hashinst = hashlib.md5()
+        if platform.python_version()[0] == "2":
+            hashinst.update(str(doc))
+        else:
+            hashinst.update(str(doc).encode('utf-8'))
+        md5sum = hashinst.hexdigest()
+    except UnicodeDecodeError as e:
+        md5sum = None
+        print(
+            "Error({}) occurred when `md5({})`, discard it.".format(
+                str(e), doc),
+            file=sys.stderr)
+    return md5sum
 
 
 def split_with_and_without_core_ops(member, cur_name):
diff --git a/tools/print_signatures.py b/tools/print_signatures.py
index cfe34fa342656d26d06cb425c71851ed0ffaf609..6de9d84379fea595aa7497f9d22ce66f0e9f0c6f 100644
--- a/tools/print_signatures.py
+++ b/tools/print_signatures.py
@@ -34,9 +34,21 @@ visited_modules = set()
 
 
 def md5(doc):
-    hash = hashlib.md5()
-    hash.update(str(doc).encode('utf-8'))
-    return hash.hexdigest()
+    try:
+        hashinst = hashlib.md5()
+        if platform.python_version()[0] == "2":
+            hashinst.update(str(doc))
+        else:
+            hashinst.update(str(doc).encode('utf-8'))
+        md5sum = hashinst.hexdigest()
+    except UnicodeDecodeError as e:
+        md5sum = None
+        print(
+            "Error({}) occurred when `md5({})`, discard it.".format(
+                str(e), doc),
+            file=sys.stderr)
+
+    return md5sum
 
 
 def get_functools_partial_spec(func):