diff --git a/Doc/library/urllib.request.rst b/Doc/library/urllib.request.rst
index 18df078..dac4176 100644
--- a/Doc/library/urllib.request.rst
+++ b/Doc/library/urllib.request.rst
@@ -175,11 +175,15 @@ The following classes are provided:
 
    *url* should be a string containing a valid URL.
 
-   *data* must be a bytes object specifying additional data to send to the
-   server, or ``None`` if no such data is needed.  Currently HTTP requests are
-   the only ones that use *data*; the HTTP request will be a POST instead of a
-   GET when the *data* parameter is provided.  *data* should be a buffer in the
-   standard :mimetype:`application/x-www-form-urlencoded` format.
+   *data* must be a :term:`bytes-like object <bytes-like object>` specifying 
+   additional data to send to the server, or ``None`` if no such data is needed. 
+   data may also be an iterable of :term:`bytes-like object <bytes-like object>`, 
+   including a dict with key of this type (this is not supported for HTTPS), and 
+   in that case Content-Length value must be specified in the headers. Currently 
+   HTTP requests are the only ones that use *data*; the HTTP request will be a 
+   POST instead of a GET when the *data* parameter is provided.  *data* should 
+   be a buffer in the standard :mimetype:`application/x-www-form-urlencoded` 
+   format.
 
    The :func:`urllib.parse.urlencode` function takes a mapping or sequence of
    2-tuples and returns a string in this format. It should be encoded to bytes
diff --git a/Lib/test/test_urllib.py b/Lib/test/test_urllib.py
index 58ca2a5..7f3bcd2 100644
--- a/Lib/test/test_urllib.py
+++ b/Lib/test/test_urllib.py
@@ -1407,8 +1407,12 @@ class RequestTests(unittest.TestCase):
         Request = urllib.request.Request
         request = Request("http://www.python.org")
         self.assertEqual(request.get_method(), 'GET')
+        request = Request("http://www.python.org", None)
+        self.assertEqual(request.get_method(), 'GET')
         request = Request("http://www.python.org", {})
         self.assertEqual(request.get_method(), 'POST')
+        request = Request("http://www.python.org", b'')
+        self.assertEqual(request.get_method(), 'POST')
 
     def test_with_method_arg(self):
         Request = urllib.request.Request
@@ -1424,6 +1428,15 @@ class RequestTests(unittest.TestCase):
         self.assertEqual(request.get_method(), 'HEAD')
 
 
+    def test_with_invalid_param_type(self):
+        Request = urllib.request.Request
+        with self.assertRaisesRegex(TypeError, "url should be of type str"):
+            request = Request(b"http://www.python.org")
+        with self.assertRaisesRegex(TypeError, "POST data cannot be of type str"):
+            request = Request("http://www.python.org", '')
+        with self.assertRaisesRegex(TypeError,"Key should be type of bytes in POST data"):
+            request = Request("http://www.python.org", {'abc': 1})
+
 class URL2PathNameTests(unittest.TestCase):
 
     def test_converting_drive_letter(self):
diff --git a/Lib/urllib/request.py b/Lib/urllib/request.py
index e6abf34..06c0e2d 100644
--- a/Lib/urllib/request.py
+++ b/Lib/urllib/request.py
@@ -353,6 +353,8 @@ class Request:
 
     @full_url.setter
     def full_url(self, url):
+        if not isinstance(url, str):
+            raise TypeError("url should be of type str")
         # unwrap('<URL:type://host/path>') --> 'type://host/path'
         self._full_url = unwrap(url)
         self._full_url, self.fragment = splittag(self._full_url)
@@ -370,6 +372,13 @@ class Request:
 
     @data.setter
     def data(self, data):
+        if isinstance(data, str):
+            raise TypeError("POST data cannot be of type str")
+
+        if type(data) is dict:
+            if any(not isinstance(k, bytes) for k in data):
+                raise TypeError("Key should be type of bytes in POST data")
+
         if data != self._data:
             self._data = data
             # issue 16464
@@ -1229,10 +1238,6 @@ class AbstractHTTPHandler(BaseHandler):
 
         if request.data is not None:  # POST
             data = request.data
-            if isinstance(data, str):
-                msg = "POST data should be bytes or an iterable of bytes. " \
-                      "It cannot be of type str."
-                raise TypeError(msg)
             if not request.has_header('Content-type'):
                 request.add_unredirected_header(
                     'Content-type',