diff --git a/graphene_django/fields.py b/graphene_django/fields.py
index e6daa88..ad9bff3 100644
--- a/graphene_django/fields.py
+++ b/graphene_django/fields.py
@@ -154,32 +154,42 @@ class DjangoConnectionField(ConnectionField):
         enforce_first_or_last,
         root,
         info,
-        **args
+        **kwargs
     ):
-        first = args.get("first")
-        last = args.get("last")
+        first = kwargs.get("first")
+        last = kwargs.get("last")
 
-        if enforce_first_or_last:
-            assert first or last, (
-                "You must provide a `first` or `last` value to properly paginate the `{}` connection."
-            ).format(info.field_name)
+        if not (first is None or first > 0):
+            raise ValueError(
+                "`first` argument must be positive, got `{first}`".format(**locals()))
+        if not (last is None or last > 0):
+            raise ValueError(
+                "`last` argument must be positive, got `{last}`".format(**locals()))
+
+        if enforce_first_or_last and not (first or last):
+            raise ValueError(
+                "You must provide a `first` or `last` value "
+                "to properly paginate the `{info.field_name}` connection.".format(**locals()))
 
         if max_limit:
             if first:
                 assert first <= max_limit, (
                     "Requesting {} records on the `{}` connection exceeds the `first` limit of {} records."
                 ).format(first, info.field_name, max_limit)
-                args["first"] = min(first, max_limit)
+                kwargs["first"] = min(first, max_limit)
 
             if last:
                 assert last <= max_limit, (
                     "Requesting {} records on the `{}` connection exceeds the `last` limit of {} records."
                 ).format(last, info.field_name, max_limit)
-                args["last"] = min(last, max_limit)
+                kwargs["last"] = min(last, max_limit)
 
-        iterable = resolver(root, info, **args)
-        queryset = cls.resolve_queryset(connection, default_manager, info, args)
-        on_resolve = partial(cls.resolve_connection, connection, queryset, args)
+            if first is None and last is None:
+                kwargs['first'] = max_limit
+
+        iterable = resolver(root, info, **kwargs)
+        queryset = cls.resolve_queryset(connection, default_manager, info, kwargs)
+        on_resolve = partial(cls.resolve_connection, connection, queryset, kwargs)
 
         if Promise.is_thenable(iterable):
             return Promise.resolve(iterable).then(on_resolve)
diff --git a/graphene_django/filter/tests/test_fields.py b/graphene_django/filter/tests/test_fields.py
index 1ffa0f4..0423e57 100644
--- a/graphene_django/filter/tests/test_fields.py
+++ b/graphene_django/filter/tests/test_fields.py
@@ -950,7 +950,7 @@ def test_filter_filterset_based_on_mixin():
                 }
             }
         }
-    """
+        """
         % reporter_1.email
     )
 
@@ -971,3 +971,41 @@ def test_filter_filterset_based_on_mixin():
 
     assert not result.errors
     assert result.data == expected
+
+
+def test_filter_with_union():
+    class ReporterType(DjangoObjectType):
+        class Meta:
+            model = Reporter
+            interfaces = (Node,)
+            filter_fields = ("first_name",)
+
+    class Query(ObjectType):
+        all_reporters = DjangoFilterConnectionField(ReporterType)
+
+        @classmethod
+        def resolve_all_reporters(cls, root, info, **kwargs):
+            ret = Reporter.objects.none() | Reporter.objects.filter(first_name="John")
+
+
+    Reporter.objects.create(first_name="John", last_name="Doe")
+
+    schema = Schema(query=Query)
+
+    query = """
+        query NodeFilteringQuery {
+            allReporters(firstName: "abc") {
+                edges {
+                    node {
+                        firstName
+                    }
+                }
+            }
+        }
+    """
+    expected = {"allReporters": {"edges": []}}
+
+    result = schema.execute(query)
+
+    assert not result.errors
+    assert result.data == expected
diff --git a/graphene_django/tests/test_query.py b/graphene_django/tests/test_query.py
index f24f84b..15345a2 100644
--- a/graphene_django/tests/test_query.py
+++ b/graphene_django/tests/test_query.py
@@ -1,23 +1,23 @@
 import base64
 import datetime
 
+import graphene
 import pytest
 from django.db import models
-from django.utils.functional import SimpleLazyObject
-from py.test import raises
-
 from django.db.models import Q
 
 from graphql_relay import to_global_id
 import graphene
+from django.utils.functional import SimpleLazyObject
 from graphene.relay import Node
+from py.test import raises
 
-from ..utils import DJANGO_FILTER_INSTALLED
-from ..compat import MissingType, JSONField
+from ..compat import JSONField, MissingType
 from ..fields import DjangoConnectionField
-from ..types import DjangoObjectType
 from ..settings import graphene_settings
-from .models import Article, CNNReporter, Reporter, Film, FilmDetails
+from ..types import DjangoObjectType
+from ..utils import DJANGO_FILTER_INSTALLED
+from .models import Article, CNNReporter, Film, FilmDetails, Reporter
 
 pytestmark = pytest.mark.django_db
 
@@ -661,7 +661,7 @@ def test_should_error_if_first_is_greater_than_max():
     assert len(result.errors) == 1
     assert str(result.errors[0]) == (
         "Requesting 101 records on the `allReporters` connection "
-        "exceeds the `first` limit of 100 records."
+        "exceeds the limit of 100 records."
     )
     assert result.data == expected
 
@@ -702,7 +702,7 @@ def test_should_error_if_last_is_greater_than_max():
     assert len(result.errors) == 1
     assert str(result.errors[0]) == (
         "Requesting 101 records on the `allReporters` connection "
-        "exceeds the `last` limit of 100 records."
+        "exceeds the limit of 100 records."
     )
     assert result.data == expected