diff --git a/backend/open_webui/models/channels.py b/backend/open_webui/models/channels.py
index 0364a123c7..754f6e3dfa 100644
--- a/backend/open_webui/models/channels.py
+++ b/backend/open_webui/models/channels.py
@@ -7,7 +7,10 @@ from open_webui.internal.db import Base, get_db
 from open_webui.models.groups import Groups
 
 from pydantic import BaseModel, ConfigDict
-from sqlalchemy import BigInteger, Boolean, Column, String, Text, JSON, case
+from sqlalchemy.dialects.postgresql import JSONB
+
+
+from sqlalchemy import BigInteger, Boolean, Column, String, Text, JSON, case, cast
 from sqlalchemy import or_, func, select, and_, text
 from sqlalchemy.sql import exists
 
@@ -293,28 +296,41 @@ class ChannelTable:
             channels = db.query(Channel).all()
             return [ChannelModel.model_validate(channel) for channel in channels]
 
-    def _has_permission(self, query, filter: dict, permission: str = "read"):
+    def _has_permission(self, db, query, filter: dict, permission: str = "read"):
         group_ids = filter.get("group_ids", [])
         user_id = filter.get("user_id")
 
-        json_group_ids = Channel.access_control[permission]["group_ids"]
+        dialect_name = db.bind.dialect.name
 
+        # Public access
         conditions = []
         if group_ids or user_id:
-            conditions.append(Channel.access_control.is_(None))
+            conditions.extend(
+                [
+                    Channel.access_control.is_(None),
+                    cast(Channel.access_control, String) == "null",
+                ]
+            )
 
+        # User-level permission
         if user_id:
             conditions.append(Channel.user_id == user_id)
 
+        # Group-level permission
         if group_ids:
             group_conditions = []
-
             for gid in group_ids:
-                # CASE: gid IN JSON array
-                # SQLite → json_extract(access_control, '$.write.group_ids') LIKE '%gid%'
-                # Postgres → access_control->'write'->'group_ids' @> '[gid]'
-                group_conditions.append(json_group_ids.contains([gid]))
-
+                if dialect_name == "sqlite":
+                    group_conditions.append(
+                        Channel.access_control[permission]["group_ids"].contains([gid])
+                    )
+                elif dialect_name == "postgresql":
+                    group_conditions.append(
+                        cast(
+                            Channel.access_control[permission]["group_ids"],
+                            JSONB,
+                        ).contains([gid])
+                    )
             conditions.append(or_(*group_conditions))
 
         if conditions:
@@ -351,7 +367,7 @@ class ChannelTable:
                 ),
             )
             query = self._has_permission(
-                query, {"user_id": user_id, "group_ids": user_group_ids}
+                db, query, {"user_id": user_id, "group_ids": user_group_ids}
             )
 
             standard_channels = query.all()
diff --git a/backend/open_webui/models/models.py b/backend/open_webui/models/models.py
index 6d3d9858bc..1c44d311ba 100755
--- a/backend/open_webui/models/models.py
+++ b/backend/open_webui/models/models.py
@@ -13,6 +13,8 @@ from pydantic import BaseModel, ConfigDict
 
 from sqlalchemy import String, cast, or_, and_, func
 from sqlalchemy.dialects import postgresql, sqlite
+
+from sqlalchemy.dialects.postgresql import JSONB
 from sqlalchemy import BigInteger, Column, Text, JSON, Boolean
 
 
@@ -220,28 +222,41 @@ class ModelsTable:
             or has_access(user_id, permission, model.access_control, user_group_ids)
         ]
 
-    def _has_write_permission(self, query, filter: dict):
+    def _has_permission(self, db, query, filter: dict, permission: str = "read"):
         group_ids = filter.get("group_ids", [])
         user_id = filter.get("user_id")
 
-        json_group_ids = Model.access_control["write"]["group_ids"]
+        dialect_name = db.bind.dialect.name
 
+        # Public access
         conditions = []
         if group_ids or user_id:
-            conditions.append(Model.access_control.is_(None))
+            conditions.extend(
+                [
+                    Model.access_control.is_(None),
+                    cast(Model.access_control, String) == "null",
+                ]
+            )
 
+        # User-level permission
         if user_id:
             conditions.append(Model.user_id == user_id)
 
+        # Group-level permission
         if group_ids:
             group_conditions = []
-
             for gid in group_ids:
-                # CASE: gid IN JSON array
-                # SQLite → json_extract(access_control, '$.write.group_ids') LIKE '%gid%'
-                # Postgres → access_control->'write'->'group_ids' @> '[gid]'
-                group_conditions.append(json_group_ids.contains([gid]))
-
+                if dialect_name == "sqlite":
+                    group_conditions.append(
+                        Model.access_control[permission]["group_ids"].contains([gid])
+                    )
+                elif dialect_name == "postgresql":
+                    group_conditions.append(
+                        cast(
+                            Model.access_control[permission]["group_ids"],
+                            JSONB,
+                        ).contains([gid])
+                    )
             conditions.append(or_(*group_conditions))
 
         if conditions:
@@ -267,15 +282,20 @@ class ModelsTable:
                         )
                     )
 
-                # Apply access control filtering
-                query = self._has_write_permission(query, filter)
-
                 view_option = filter.get("view_option")
                 if view_option == "created":
                     query = query.filter(Model.user_id == user_id)
                 elif view_option == "shared":
                     query = query.filter(Model.user_id != user_id)
 
+                # Apply access control filtering
+                query = self._has_permission(
+                    db,
+                    query,
+                    filter,
+                    permission="write",
+                )
+
                 tag = filter.get("tag")
                 if tag:
                     # TODO: This is a simple implementation and should be improved for performance