2 files changed, 1 insertions, 10 deletions
diff --git a/django/db/backends/postgresql/features.py b/django/db/backends/postgresql/features.py
index fad87081b0..67c04d89dc 100644
--- a/django/db/backends/postgresql/features.py
+++ b/django/db/backends/postgresql/features.py
@@ -52,6 +52,7 @@ class DatabaseFeatures(BaseDatabaseFeatures):
     $$ LANGUAGE plpgsql;"""
     requires_casted_case_in_updates = True
     supports_over_clause = True
+    only_supports_unbounded_with_preceding_and_following = True
     supports_aggregate_filter_clause = True
     supported_explain_formats = {'JSON', 'TEXT', 'XML', 'YAML'}
     validates_explain_options = False  # A query will error on invalid options.
diff --git a/django/db/backends/postgresql/operations.py b/django/db/backends/postgresql/operations.py
index ee7787c560..e8355a0e58 100644
--- a/django/db/backends/postgresql/operations.py
+++ b/django/db/backends/postgresql/operations.py
@@ -1,7 +1,6 @@
 from psycopg2.extras import Inet
 
 from django.conf import settings
-from django.db import NotSupportedError
 from django.db.backends.base.operations import BaseDatabaseOperations
 
 
@@ -275,15 +274,6 @@ class DatabaseOperations(BaseDatabaseOperations):
             return "(interval '1 day' * (%s - %s))" % (lhs_sql, rhs_sql), params
         return super().subtract_temporals(internal_type, lhs, rhs)
 
-    def window_frame_range_start_end(self, start=None, end=None):
-        start_, end_ = super().window_frame_range_start_end(start, end)
-        if (start and start < 0) or (end and end > 0):
-            raise NotSupportedError(
-                'PostgreSQL only supports UNBOUNDED together with PRECEDING '
-                'and FOLLOWING.'
-            )
-        return start_, end_
-
     def explain_query_prefix(self, format=None, **options):
         prefix = super().explain_query_prefix(format)
         extra = {}