diff --git a/connexion/apis/aiohttp_api.py b/connexion/apis/aiohttp_api.py
index 0fdffc604..6adaf5101 100644
--- a/connexion/apis/aiohttp_api.py
+++ b/connexion/apis/aiohttp_api.py
@@ -305,13 +305,52 @@ async def get_request(cls, req):
         :rtype: ConnexionRequest
         """
         url = str(req.url)
-        logger.debug('Getting data and status code',
-                     extra={'can_read_body': req.can_read_body, 'url': url})
+
+        logger.debug(
+            'Getting data and status code',
+            extra={
+                # has_body | can_read_body report if
+                # body has been read or not
+                # body_exists refers to underlying stream of data
+                'body_exists': req.body_exists,
+                'can_read_body': req.can_read_body,
+                'content_type': req.content_type,
+                'url': url,
+            },
+        )
 
         query = parse_qs(req.rel_url.query_string)
         headers = req.headers
         body = None
-        if req.body_exists:
+
+        # Note: if request is not 'application/x-www-form-urlencoded' nor 'multipart/form-data',
+        #       then `post_data` will be left an empty dict and the stream will not be consumed.
+        post_data = await req.post()
+
+        files = {}
+        form = {}
+
+        if post_data:
+            logger.debug('Reading multipart data from request')
+            for k, v in post_data.items():
+                if isinstance(v, web.FileField):
+                    if k in files:
+                        # if multiple files arrive under the same name in the
+                        # request, downstream requires that we put them all into
+                        # a list under the same key in the files dict.
+                        if isinstance(files[k], list):
+                            files[k].append(v)
+                        else:
+                            files[k] = [files[k], v]
+                    else:
+                        files[k] = v
+                else:
+                    # put normal fields as an array, that's how werkzeug does that for Flask
+                    # and that's what Connexion expects in its processing functions
+                    form[k] = [v]
+            body = b''
+        else:
+            logger.debug('Reading data from request')
             body = await req.read()
 
         return ConnexionRequest(url=url,
@@ -321,7 +360,8 @@ async def get_request(cls, req):
                                 headers=headers,
                                 body=body,
                                 json_getter=lambda: cls.jsonifier.loads(body),
-                                files={},
+                                form=form,
+                                files=files,
                                 context=req)
 
     @classmethod
diff --git a/connexion/operations/openapi.py b/connexion/operations/openapi.py
index d6f958b5e..f29877217 100644
--- a/connexion/operations/openapi.py
+++ b/connexion/operations/openapi.py
@@ -272,12 +272,21 @@ def body_definition(self):
         return {}
 
     def _get_body_argument(self, body, arguments, has_kwargs, sanitize):
+        if len(arguments) <= 0 and not has_kwargs:
+            return {}
+
         x_body_name = sanitize(self.body_schema.get('x-body-name', 'body'))
+
+        # if the body came in null, and the schema says it can be null, we decide
+        # to include no value for the body argument, rather than the default body
         if is_nullable(self.body_schema) and is_null(body):
-            return {x_body_name: None}
+            if x_body_name in arguments or has_kwargs:
+                return {x_body_name: None}
+            return {}
 
+        # now determine the actual value for the body (whether it came in or is default)
         default_body = self.body_schema.get('default', {})
-        body_props = {k: {"schema": v} for k, v
+        body_props = {sanitize(k): {"schema": v} for k, v
                       in self.body_schema.get("properties", {}).items()}
 
         # by OpenAPI specification `additionalProperties` defaults to `true`
@@ -287,11 +296,13 @@ def _get_body_argument(self, body, arguments, has_kwargs, sanitize):
         if body is None:
             body = deepcopy(default_body)
 
+        # if the body isn't even an object, then none of the concerns below matter
         if self.body_schema.get("type") != "object":
             if x_body_name in arguments or has_kwargs:
                 return {x_body_name: body}
             return {}
 
+        # supply the initial defaults and convert all values to the proper types by schema
         body_arg = deepcopy(default_body)
         body_arg.update(body or {})
 
diff --git a/tests/aiohttp/test_aiohttp_multipart.py b/tests/aiohttp/test_aiohttp_multipart.py
new file mode 100644
index 000000000..7f80b7388
--- /dev/null
+++ b/tests/aiohttp/test_aiohttp_multipart.py
@@ -0,0 +1,118 @@
+import os
+from pathlib import Path
+
+import pytest
+from connexion import AioHttpApp
+
+import aiohttp
+
+try:
+    import ujson as json
+except ImportError:
+    import json
+
+
+@pytest.fixture
+def aiohttp_app(aiohttp_api_spec_dir):
+    app = AioHttpApp(__name__, port=5001,
+                     specification_dir=aiohttp_api_spec_dir,
+                     debug=True)
+    app.add_api(
+        'openapi_multipart.yaml',
+        validate_responses=True,
+        strict_validation=True,
+        pythonic_params=True,
+        pass_context_arg_name='request_ctx',
+    )
+    return app
+
+
+async def test_single_file_upload(aiohttp_app, aiohttp_client):
+    app_client = await aiohttp_client(aiohttp_app.app)
+
+    resp = await app_client.post(
+        '/v1.0/upload_file',
+        data=aiohttp.FormData(fields=[('myfile', open(__file__, 'rb'))])(),
+    )
+
+    data = await resp.json()
+    assert resp.status == 200
+    assert data['fileName'] == f'{__name__}.py'
+    assert data['myfile_content'] == Path(__file__).read_bytes().decode('utf8')
+
+
+async def test_many_files_upload(aiohttp_app, aiohttp_client):
+    app_client = await aiohttp_client(aiohttp_app.app)
+
+    dir_name = os.path.dirname(__file__)
+    files_field = [
+        ('myfiles', open(f'{dir_name}/{file_name}', 'rb')) \
+            for file_name in sorted(os.listdir(dir_name)) if file_name.endswith('.py')
+    ]
+
+    form_data = aiohttp.FormData(fields=files_field)
+
+    resp = await app_client.post(
+        '/v1.0/upload_files',
+        data=form_data(),
+    )
+
+    data = await resp.json()
+
+    assert resp.status == 200
+    assert data['files_count'] == len(files_field)
+    assert data['myfiles_content'] == [
+        Path(f'{dir_name}/{file_name}').read_bytes().decode('utf8') \
+            for file_name in sorted(os.listdir(dir_name)) if file_name.endswith('.py')
+    ]
+
+
+async def test_mixed_multipart_single_file(aiohttp_app, aiohttp_client):
+    app_client = await aiohttp_client(aiohttp_app.app)
+
+    form_data = aiohttp.FormData()
+    form_data.add_field('dir_name', os.path.dirname(__file__))
+    form_data.add_field('myfile', open(__file__, 'rb'))
+
+    resp = await app_client.post(
+        '/v1.0/mixed_single_file',
+        data=form_data(),
+    )
+
+    data = await resp.json()
+
+    assert resp.status == 200
+    assert data['dir_name'] == os.path.dirname(__file__)
+    assert data['fileName'] == f'{__name__}.py'
+    assert data['myfile_content'] == Path(__file__).read_bytes().decode('utf8')
+
+
+
+async def test_mixed_multipart_many_files(aiohttp_app, aiohttp_client):
+    app_client = await aiohttp_client(aiohttp_app.app)
+
+    dir_name = os.path.dirname(__file__)
+    files_field = [
+        ('myfiles', open(f'{dir_name}/{file_name}', 'rb')) \
+            for file_name in sorted(os.listdir(dir_name)) if file_name.endswith('.py')
+    ]
+
+    form_data = aiohttp.FormData(fields=files_field)
+    form_data.add_field('dir_name', os.path.dirname(__file__))
+    form_data.add_field('test_count', str(len(files_field)))
+
+    resp = await app_client.post(
+        '/v1.0/mixed_many_files',
+        data=form_data(),
+    )
+
+    data = await resp.json()
+
+    assert resp.status == 200
+    assert data['dir_name'] == os.path.dirname(__file__)
+    assert data['test_count'] == len(files_field)
+    assert data['files_count'] == len(files_field)
+    assert data['myfiles_content'] == [
+        Path(f'{dir_name}/{file_name}').read_bytes().decode('utf8') \
+            for file_name in sorted(os.listdir(dir_name)) if file_name.endswith('.py')
+    ]
diff --git a/tests/api/test_parameters.py b/tests/api/test_parameters.py
index b60e75580..ea1e48a54 100644
--- a/tests/api/test_parameters.py
+++ b/tests/api/test_parameters.py
@@ -387,6 +387,9 @@ def test_nullable_parameter(simple_app):
     resp = app_client.put('/v1.0/nullable-parameters', data="None", headers=headers)
     assert json.loads(resp.data.decode('utf-8', 'replace')) == 'it was None'
 
+    resp = app_client.put('/v1.0/nullable-parameters-noargs', data="None", headers=headers)
+    assert json.loads(resp.data.decode('utf-8', 'replace')) == 'hello'
+
 
 def test_args_kwargs(simple_app):
     app_client = simple_app.app.test_client()
@@ -398,6 +401,16 @@ def test_args_kwargs(simple_app):
     assert resp.status_code == 200
     assert json.loads(resp.data.decode('utf-8', 'replace')) == {'foo': 'a'}
 
+    if simple_app._spec_file == 'openapi.yaml':
+        body = { 'foo': 'a', 'bar': 'b' }
+        resp = app_client.post(
+            '/v1.0/body-params-as-kwargs',
+            data=json.dumps(body),
+            headers={'Content-Type': 'application/json'})
+        assert resp.status_code == 200
+        # having only kwargs, the handler would have been passed 'body'
+        assert json.loads(resp.data.decode('utf-8', 'replace')) == {'body': {'foo': 'a', 'bar': 'b'}, }
+
 
 def test_param_sanitization(simple_app):
     app_client = simple_app.app.test_client()
diff --git a/tests/fakeapi/aiohttp_handlers.py b/tests/fakeapi/aiohttp_handlers.py
index e37af67fc..a61cc0019 100755
--- a/tests/fakeapi/aiohttp_handlers.py
+++ b/tests/fakeapi/aiohttp_handlers.py
@@ -105,3 +105,45 @@ async def get_date():
 
 async def get_uuid():
     return ConnexionResponse(body={'value': uuid.UUID(hex='e7ff66d0-3ec2-4c4e-bed0-6e4723c24c51')})
+
+
+async def aiohttp_multipart_single_file(myfile):
+    return aiohttp.web.json_response(
+        data={
+            'fileName': myfile.filename,
+            'myfile_content': myfile.file.read().decode('utf8')
+        },
+    )
+
+
+async def aiohttp_multipart_many_files(myfiles):
+    return aiohttp.web.json_response(
+        data={
+            'files_count': len(myfiles),
+            'myfiles_content': [ f.file.read().decode('utf8') for f in myfiles ]
+        },
+    )
+
+
+async def aiohttp_multipart_mixed_single_file(myfile, body):
+    dir_name = body['dir_name']
+    return aiohttp.web.json_response(
+        data={
+            'dir_name': dir_name,
+            'fileName': myfile.filename,
+            'myfile_content': myfile.file.read().decode('utf8'),
+        },
+    )
+
+
+async def aiohttp_multipart_mixed_many_files(myfiles, body):
+    dir_name = body['dir_name']
+    test_count = body['test_count']
+    return aiohttp.web.json_response(
+        data={
+            'files_count': len(myfiles),
+            'dir_name': dir_name,
+            'test_count': test_count,
+            'myfiles_content': [ f.file.read().decode('utf8') for f in myfiles ]
+        },
+    )
diff --git a/tests/fakeapi/hello/__init__.py b/tests/fakeapi/hello/__init__.py
index 773d64055..0645b5ef7 100644
--- a/tests/fakeapi/hello/__init__.py
+++ b/tests/fakeapi/hello/__init__.py
@@ -402,6 +402,9 @@ def test_nullable_param_put(contents):
         return 'it was None'
     return contents
 
+def test_nullable_param_put_noargs(dummy=''):
+    return 'hello'
+
 
 def test_custom_json_response():
     return {'theResult': DummyClass()}, 200
@@ -459,6 +462,9 @@ def optional_auth(**kwargs):
 def test_args_kwargs(*args, **kwargs):
     return kwargs
 
+def test_args_kwargs_post(*args, **kwargs):
+    return kwargs
+
 
 def test_param_sanitization(query=None, form=None):
     result = {}
diff --git a/tests/fixtures/aiohttp/openapi_multipart.yaml b/tests/fixtures/aiohttp/openapi_multipart.yaml
new file mode 100644
index 000000000..f4374b6a3
--- /dev/null
+++ b/tests/fixtures/aiohttp/openapi_multipart.yaml
@@ -0,0 +1,132 @@
+---
+openapi: 3.0.0
+servers:
+  - url: /v1.0
+info:
+  title: "{{title}}"
+  version: "1.0"
+paths:
+  "/upload_file":
+    post:
+      summary: Uploads single file
+      description: Handles multipart file upload.
+      operationId: fakeapi.aiohttp_handlers.aiohttp_multipart_single_file
+      responses:
+        "200":
+          description: OK response
+          content:
+            'application/json':
+              schema:
+                type: object
+                properties:
+                  fileName:
+                    type: string
+        default:
+          description: unexpected error
+      requestBody:
+        required: true
+        content:
+          multipart/form-data:
+            schema:
+              type: object
+              properties:
+                myfile:
+                  type: string
+                  format: binary
+  "/upload_files":
+    post:
+      summary: Uploads many files
+      description: Handles multipart file upload.
+      operationId: fakeapi.aiohttp_handlers.aiohttp_multipart_many_files
+      responses:
+        "200":
+          description: OK response
+          content:
+            'application/json':
+              schema:
+                type: object
+                properties:
+                  files_count:
+                    type: number
+        default:
+          description: unexpected error
+      requestBody:
+        required: true
+        content:
+          multipart/form-data:
+            schema:
+              type: object
+              properties:
+                myfiles:
+                  type: array
+                  items:
+                    type: string
+                    format: binary
+  "/mixed_single_file":
+    post:
+      summary: Reads multipart data
+      description: Handles multipart data reading
+      operationId: fakeapi.aiohttp_handlers.aiohttp_multipart_mixed_single_file
+      responses:
+        "200":
+          description: OK response
+          content:
+            'application/json':
+              schema:
+                type: object
+                properties:
+                  dir_name:
+                    type: string
+                  fileName:
+                    type: string
+        default:
+          description: unexpected error
+      requestBody:
+        required: true
+        content:
+          multipart/form-data:
+            schema:
+              type: object
+              properties:
+                dir_name:
+                  type: string
+                myfile:
+                  type: string
+                  format: binary
+  "/mixed_many_files":
+    post:
+      summary: Reads multipart data
+      description: Handles multipart data reading
+      operationId: fakeapi.aiohttp_handlers.aiohttp_multipart_mixed_many_files
+      responses:
+        "200":
+          description: OK response
+          content:
+            'application/json':
+              schema:
+                type: object
+                properties:
+                  dir_name:
+                    type: string
+                  test_count:
+                    type: number
+                  files_count:
+                    type: number
+        default:
+          description: unexpected error
+      requestBody:
+        required: true
+        content:
+          multipart/form-data:
+            schema:
+              type: object
+              properties:
+                dir_name:
+                  type: string
+                test_count:
+                  type: number
+                myfiles:
+                  type: array
+                  items:
+                    type: string
+                    format: binary
diff --git a/tests/fixtures/simple/openapi.yaml b/tests/fixtures/simple/openapi.yaml
index 7ff1ad91e..82e253340 100644
--- a/tests/fixtures/simple/openapi.yaml
+++ b/tests/fixtures/simple/openapi.yaml
@@ -845,6 +845,24 @@ paths:
       responses:
         '200':
           description: OK
+  /nullable-parameters-noargs:
+    put:
+      operationId: fakeapi.hello.test_nullable_param_put_noargs
+      responses:
+        '200':
+          description: OK
+      requestBody:
+        content:
+          application/json:
+            schema:
+              nullable: true
+              x-body-name: contents
+              type: object
+              properties:
+                name:
+                  type: string
+        description: Just a testing parameter.
+        required: true
   /custom-json-response:
     get:
       operationId: fakeapi.hello.test_custom_json_response
@@ -896,6 +914,25 @@ paths:
             application/json:
               schema:
                 type: object
+  /body-params-as-kwargs:
+    post:
+      operationId: fakeapi.hello.test_args_kwargs_post
+      requestBody:
+        content:
+          application/json:
+            schema:
+              type: object
+              properties:
+                foo:
+                  type: string
+              additionalProperties: true
+      responses:
+        '200':
+          description: Return kwargs
+          content:
+            application/json:
+              schema:
+                type: object
   /text-request:
     post:
       operationId: fakeapi.hello.get_data_as_text
diff --git a/tests/fixtures/simple/swagger.yaml b/tests/fixtures/simple/swagger.yaml
index de3db771e..1030b0685 100644
--- a/tests/fixtures/simple/swagger.yaml
+++ b/tests/fixtures/simple/swagger.yaml
@@ -677,6 +677,26 @@ paths:
         200:
           description: OK
 
+  /nullable-parameters-noargs:
+    put:
+      operationId: fakeapi.hello.test_nullable_param_put_noargs
+      produces:
+        - application/json
+      parameters:
+        - name: contents
+          description: Just a testing parameter.
+          in: body
+          x-nullable: true
+          required: true
+          schema:
+              type: object
+              properties:
+                name:
+                  type: string
+      responses:
+        200:
+          description: OK
+
   /custom-json-response:
     get:
       operationId: fakeapi.hello.test_custom_json_response
@@ -731,6 +751,30 @@ paths:
           schema:
             type: object
 
+  /body-params-as-kwargs:
+    post:
+      operationId: fakeapi.hello.test_args_kwargs_post
+      produces:
+        - application/json
+      parameters:
+        - name: $body
+          description: Just a testing parameter in the body
+          in: body
+          required: true
+          schema:
+            type: object
+            properties:
+              foo:
+                type: string
+              bar:
+                type: string
+            additionalProperties: true
+      responses:
+        200:
+          description: Return kwargs
+          schema:
+            type: object
+
   /text-request:
     post:
       operationId: fakeapi.hello.get_data_as_text