Fix database initialization issue and add delay

after upgrade

src/backend/langflow/services/database/service.py

@@ -5,16 +5,17 @@ from typing import TYPE_CHECKING
 import sqlalchemy as sa
 from alembic import command, util
 from alembic.config import Config
+from loguru import logger
+from sqlalchemy import inspect
+from sqlalchemy.exc import OperationalError
+from sqlmodel import Session, SQLModel, create_engine, text
+
 from langflow.services.base import Service
 from langflow.services.database import models  # noqa
 from langflow.services.database.models.user.crud import get_user_by_username
 from langflow.services.database.utils import Result, TableResults
 from langflow.services.deps import get_settings_service
 from langflow.services.utils import teardown_superuser
-from loguru import logger
-from sqlalchemy import inspect
-from sqlalchemy.exc import OperationalError
-from sqlmodel import Session, SQLModel, create_engine
 
 if TYPE_CHECKING:
     from sqlalchemy.engine import Engine
@@ -130,7 +131,7 @@ class DatabaseService(Service):
             # If the table does not exist it throws an error
             # so we need to catch it
             try:
-                session.execute("SELECT * FROM alembic_version")
+                session.exec(text("SELECT * FROM alembic_version"))
             except Exception:
                 logger.info("Alembic not initialized")
                 try:
@@ -150,6 +151,7 @@ class DatabaseService(Service):
         except Exception as exc:
             if isinstance(exc, util.exc.CommandError) or isinstance(exc, util.exc.AutogenerateDiffsDetected):
                 command.upgrade(alembic_cfg, "head")
+                time.sleep(3)
 
         try:
             command.check(alembic_cfg)