davies's comment.

Author: yhuai

python/pyspark/sql/readwriter.py

@@ -339,7 +339,7 @@ def json(self, path, mode=None):
 
         >>> df.write.json(os.path.join(tempfile.mkdtemp(), 'data'))
         """
-        self._jwrite.mode(mode).json(path)
+        self.mode(mode)._jwrite.json(path)
 
     @since(1.4)
     def parquet(self, path, mode=None, partitionBy=()):