diff --git a/api/core/helper/credential_utils.py b/api/core/helper/credential_utils.py
index b5f68039d7b..e8f3ba0a547 100644
--- a/api/core/helper/credential_utils.py
+++ b/api/core/helper/credential_utils.py
@@ -10,18 +10,21 @@ def is_credential_exists(credential_id: str, credential_type: "PluginCredentialT
     """
     Check if the credential still exists in the database.
 
+    Uses the configured SQLAlchemy session factory instead of Flask-SQLAlchemy's
+    ``db.engine`` because workflow graph node construction may run without an
+    active Flask application context.
+
     :param credential_id: The credential ID to check
     :param credential_type: The type of credential (MODEL or TOOL)
     :return: True if credential exists, False otherwise
     """
     from sqlalchemy import select
-    from sqlalchemy.orm import Session
 
-    from extensions.ext_database import db
+    from core.db import session_factory
     from models.provider import ProviderCredential, ProviderModelCredential
     from models.tools import BuiltinToolProvider
 
-    with Session(db.engine) as session:
+    with session_factory.create_session() as session:
         if credential_type == PluginCredentialType.MODEL:
             # Check both pre-defined and custom model credentials using a single UNION query
             stmt = (
diff --git a/api/tests/unit_tests/core/helper/test_credential_utils.py b/api/tests/unit_tests/core/helper/test_credential_utils.py
index dd10f81b02a..3311bbb006a 100644
--- a/api/tests/unit_tests/core/helper/test_credential_utils.py
+++ b/api/tests/unit_tests/core/helper/test_credential_utils.py
@@ -114,10 +114,11 @@ def test_is_credential_exists_by_type(
     scalar_result: str | None,
     expected: bool,
 ) -> None:
-    mocker.patch("extensions.ext_database.db", new=SimpleNamespace(engine=object()))
-    session_cls = mocker.patch("sqlalchemy.orm.Session")
-    session = session_cls.return_value.__enter__.return_value
+    session = mocker.MagicMock()
     session.scalar.return_value = scalar_result
+    session_context = mocker.MagicMock()
+    session_context.__enter__.return_value = session
+    mocker.patch("core.db.session_factory.create_session", return_value=session_context)
 
     result = is_credential_exists("cred-1", credential_type)
 
@@ -128,11 +129,33 @@ def test_is_credential_exists_by_type(
 def test_is_credential_exists_returns_false_for_unknown_type(
     mocker: MockerFixture,
 ) -> None:
-    mocker.patch("extensions.ext_database.db", new=SimpleNamespace(engine=object()))
-    session_cls = mocker.patch("sqlalchemy.orm.Session")
-    session = session_cls.return_value.__enter__.return_value
+    session = mocker.MagicMock()
+    session_context = mocker.MagicMock()
+    session_context.__enter__.return_value = session
+    mocker.patch("core.db.session_factory.create_session", return_value=session_context)
 
     result = is_credential_exists("cred-1", cast(PluginCredentialType, "unknown"))
 
     assert result is False
     session.scalar.assert_not_called()
+
+
+def test_is_credential_exists_uses_configured_session_factory_without_flask_app_context(
+    mocker: MockerFixture,
+) -> None:
+    class RaisingDB:
+        @property
+        def engine(self):
+            raise RuntimeError("Working outside of application context.")
+
+    session = mocker.MagicMock()
+    session.scalar.return_value = "model-credential"
+    session_context = mocker.MagicMock()
+    session_context.__enter__.return_value = session
+    create_session = mocker.patch("core.db.session_factory.create_session", return_value=session_context)
+    mocker.patch("extensions.ext_database.db", new=RaisingDB())
+
+    result = is_credential_exists("cred-1", PluginCredentialType.MODEL)
+
+    assert result is True
+    create_session.assert_called_once_with()