进行中文搜索时出现错误

以下是出错的信息
Traceback (most recent call last):
File "/base/python_runtime/python_lib/versions/1/google/appengine/ext/webapp/__init__.py", line 511, in __call__
handler.get(*groups)
File "/base/data/home/apps/v2ex/1.343772786028903438/main.py", line 636, in get
node = GetKindByName('Node', q.lower())
File "/base/data/home/apps/v2ex/1.343772786028903438/v2ex/babel/da/__init__.py", line 34, in GetKindByName
if q.count() == 1:
File "/base/python_runtime/python_lib/versions/1/google/appengine/ext/db/__init__.py", line 1717, in count
result = raw_query.Count(limit=limit, rpc=rpc)
File "/base/python_runtime/python_lib/versions/1/google/appengine/api/datastore.py", line 1271, in Count
req = self._ToPb(limit=limit)
File "/base/python_runtime/python_lib/versions/1/google/appengine/api/datastore.py", line 1487, in _ToPb
props = datastore_types.ToPropertyPb(name, values)
File "/base/python_runtime/python_lib/versions/1/google/appengine/api/datastore_types.py", line 1499, in ToPropertyPb
pbvalue = pack_prop(name, v, pb.mutable_value())
File "/base/python_runtime/python_lib/versions/1/google/appengine/api/datastore_types.py", line 1322, in PackString
pbvalue.set_stringvalue(unicode(value).encode('utf-8'))
UnicodeDecodeError: 'ascii' codec can't decode byte 0xe4 in position 0: ordinal not in range(128)