file_ = Filenames._get(self._files_p)
         self._move_to_next(self._files_p)
-        return file_.decode('utf-8', errors='ignore')
+        return file_.decode('utf-8', 'ignore')
     next = __next__ # python2.x iterator protocol compatibility
 
     def __len__(self):
 
             raise NotmuchError(STATUS.NOT_INITIALIZED)
 
         while self._valid(self._files):
-            yield Filenames._get(self._files).decode('utf-8', errors='ignore')
+            yield Filenames._get(self._files).decode('utf-8', 'ignore')
             self._move_to_next(self._files)
 
         self._files = None
 
         """
         if self._msg is None:
             raise NotmuchError(STATUS.NOT_INITIALIZED)
-        return Message._get_message_id(self._msg).decode('utf-8', errors='ignore')
+        return Message._get_message_id(self._msg).decode('utf-8', 'ignore')
 
     def get_thread_id(self):
         """Returns the thread ID
         if self._msg is None:
             raise NotmuchError(STATUS.NOT_INITIALIZED)
 
-        return Message._get_thread_id(self._msg).decode('utf-8', errors='ignore')
+        return Message._get_thread_id(self._msg).decode('utf-8', 'ignore')
 
     def get_replies(self):
         """Gets all direct replies to this message as :class:`Messages`
         header = Message._get_header(self._msg, _str(header))
         if header == None:
             raise NotmuchError(STATUS.NULL_POINTER)
-        return header.decode('UTF-8', errors='ignore')
+        return header.decode('UTF-8', 'ignore')
 
     def get_filename(self):
         """Returns the file path of the message file
         """
         if self._msg is None:
             raise NotmuchError(STATUS.NOT_INITIALIZED)
-        return Message._get_filename(self._msg).decode('utf-8', errors='ignore')
+        return Message._get_filename(self._msg).decode('utf-8', 'ignore')
 
     def get_filenames(self):
         """Get all filenames for the email corresponding to 'message'
 
         """
         if self._thread is None:
             raise NotmuchError(STATUS.NOT_INITIALIZED)
-        return Thread._get_thread_id(self._thread).decode('utf-8', errors='ignore')
+        return Thread._get_thread_id(self._thread).decode('utf-8', 'ignore')
 
     _get_total_messages = nmlib.notmuch_thread_get_total_messages
     _get_total_messages.argtypes = [NotmuchThreadP]
         authors = Thread._get_authors(self._thread)
         if authors is None:
             return None
-        return authors.decode('UTF-8', errors='ignore')
+        return authors.decode('UTF-8', 'ignore')
 
     def get_subject(self):
         """Returns the Subject of 'thread'
         subject = Thread._get_subject(self._thread)
         if subject is None:
             return None
-        return subject.decode('UTF-8', errors='ignore')
+        return subject.decode('UTF-8', 'ignore')
 
     def get_newest_date(self):
         """Returns time_t of the newest message date