diff --git a/rest_framework/parsers.py b/rest_framework/parsers.py
index c635505a4..23387dffb 100644
--- a/rest_framework/parsers.py
+++ b/rest_framework/parsers.py
@@ -12,7 +12,7 @@ from django.http.multipartparser import MultiPartParser as DjangoMultiPartParser
 from django.http.multipartparser import MultiPartParserError, parse_header, ChunkIter
 from rest_framework.compat import etree, six, yaml
 from rest_framework.exceptions import ParseError
-from rest_framework.renderers import UnicodeJSONRenderer
+from rest_framework import renderers
 import json
 import datetime
 import decimal
@@ -32,8 +32,6 @@ class BaseParser(object):
 
     media_type = None
 
-    supports_html_forms = False
-
     def parse(self, stream, media_type=None, parser_context=None):
         """
         Given a stream to read from, return the parsed representation.
@@ -49,7 +47,7 @@ class JSONParser(BaseParser):
     """
 
     media_type = 'application/json'
-    renderer_class = UnicodeJSONRenderer
+    renderer_class = renderers.UnicodeJSONRenderer
 
     def parse(self, stream, media_type=None, parser_context=None):
         """
@@ -94,7 +92,6 @@ class FormParser(BaseParser):
     """
 
     media_type = 'application/x-www-form-urlencoded'
-    supports_html_forms = True
 
     def parse(self, stream, media_type=None, parser_context=None):
         """
@@ -113,7 +110,6 @@ class MultiPartParser(BaseParser):
     """
 
     media_type = 'multipart/form-data'
-    supports_html_forms = True
 
     def parse(self, stream, media_type=None, parser_context=None):
         """
@@ -134,7 +130,7 @@ class MultiPartParser(BaseParser):
             data, files = parser.parse()
             return DataAndFiles(data, files)
         except MultiPartParserError as exc:
-            raise ParseError('Multipart form parse error - %s' % six.u(exc))
+            raise ParseError('Multipart form parse error - %s' % six.u(exc.strerror))
 
 
 class XMLParser(BaseParser):
diff --git a/rest_framework/renderers.py b/rest_framework/renderers.py
index cc8de9590..cd55c7830 100644
--- a/rest_framework/renderers.py
+++ b/rest_framework/renderers.py
@@ -21,7 +21,7 @@ from rest_framework.compat import six
 from rest_framework.compat import smart_text
 from rest_framework.compat import yaml
 from rest_framework.settings import api_settings
-from rest_framework.request import clone_request
+from rest_framework.request import clone_request, is_form_media_type
 from rest_framework.utils import encoders
 from rest_framework.utils.breadcrumbs import get_breadcrumbs
 from rest_framework import exceptions, status, VERSION
@@ -482,7 +482,7 @@ class BrowsableAPIRenderer(BaseRenderer):
         if method in ('DELETE', 'OPTIONS'):
             return True  # Don't actually need to return a form
 
-        if not getattr(view, 'get_serializer', None) or not any(parser.supports_html_forms for parser in view.parser_classes):
+        if not getattr(view, 'get_serializer', None) or not any(is_form_media_type(parser.media_type) for parser in view.parser_classes):
             return
 
         serializer = view.get_serializer(instance=obj)
@@ -565,11 +565,16 @@ class BrowsableAPIRenderer(BaseRenderer):
         obj = getattr(view, 'object', None)
         if getattr(view, 'get_serializer', None):
             serializer = view.get_serializer(instance=obj)
+            for field_name, field in serializer.fields.items():
+                if field.read_only:
+                    del serializer.fields[field_name]
         else:
             serializer = None
 
         parsers = []
         for parser_class in view.parser_classes:
+            if is_form_media_type(parser_class.media_type):
+                continue
             content = None
             renderer_class = getattr(parser_class, 'renderer_class', None)
             if renderer_class and serializer:
@@ -650,3 +655,4 @@ class MultiPartRenderer(BaseRenderer):
 
     def render(self, data, accepted_media_type=None, renderer_context=None):
         return encode_multipart(self.BOUNDARY, data)
+
diff --git a/rest_framework/serializers.py b/rest_framework/serializers.py
index 202d3a096..abff68983 100644
--- a/rest_framework/serializers.py
+++ b/rest_framework/serializers.py
@@ -304,8 +304,6 @@ class BaseSerializer(WritableField):
         ret.empty = obj is None
 
         for field_name, field in self.fields.items():
-            if obj is None and field.read_only:
-                continue
             field.initialize(parent=self, field_name=field_name)
             key = self.get_field_key(field_name)
             value = field.field_to_native(obj, field_name)
diff --git a/rest_framework/tests/test_serializer.py b/rest_framework/tests/test_serializer.py
index 7c2a276ed..c24976603 100644
--- a/rest_framework/tests/test_serializer.py
+++ b/rest_framework/tests/test_serializer.py
@@ -158,7 +158,7 @@ class BasicTests(TestCase):
             'email': '',
             'content': '',
             'created': None,
-            #'sub_comment': ''
+            'sub_comment': ''
         }
         self.assertEqual(serializer.data, expected)