diff --git a/backend/open_webui/models/oauth_sessions.py b/backend/open_webui/models/oauth_sessions.py
index b0e465dbe..a2da2f884 100644
--- a/backend/open_webui/models/oauth_sessions.py
+++ b/backend/open_webui/models/oauth_sessions.py
@@ -123,7 +123,7 @@ class OAuthSessionTable:
                         "user_id": user_id,
                         "provider": provider,
                         "token": self._encrypt_token(token),
-                        "expires_at": token.get("expires_at"),
+                        "expires_at": int(token.get("expires_at")) if token.get("expires_at") else None,
                         "created_at": current_time,
                         "updated_at": current_time,
                     }
diff --git a/backend/open_webui/utils/models.py b/backend/open_webui/utils/models.py
index a87a7487e..ff5b61069 100644
--- a/backend/open_webui/utils/models.py
+++ b/backend/open_webui/utils/models.py
@@ -340,7 +340,9 @@ def check_model_access(user, model):
     else:
         model_info = Models.get_model_by_id(model.get("id"))
         if not model_info:
-            raise Exception("Model not found")
+            # Model not in database (e.g., function/pipe models like Letta agents)
+            # Allow access by default
+            return
         elif not (
             user.id == model_info.user_id
             or has_access(
@@ -384,6 +386,10 @@ def get_filtered_models(models, user):
                     )
                 ):
                     filtered_models.append(model)
+            else:
+                # Model not in database (e.g., function/pipe models like Letta agents)
+                # Allow through by default
+                filtered_models.append(model)
 
         return filtered_models
     else: