diff --git a/shared/datastore/src/connect_minio.py b/shared/datastore/src/connect_minio.py
index aeef685..7dadb4e 100644
--- a/shared/datastore/src/connect_minio.py
+++ b/shared/datastore/src/connect_minio.py
@@ -19,10 +19,10 @@ def connect_minio() -> Minio:
     }
     check_env(var_list)
     # prepare arguments
-    minio_endpoint = os.getenv('MINIO_ENDPOINT', default='')
-    minio_access_key = os.getenv('MINIO_ACCESS_KEY', default='')
-    minio_secret_key = os.getenv('MINIO_SECRET_KEY', default='')
-    minio_bucket_name = os.getenv('MINIO_BUCKET_NAME', default='')
+    minio_endpoint = str(os.getenv('MINIO_ENDPOINT'))
+    minio_access_key = str(os.getenv('MINIO_ACCESS_KEY'))
+    minio_secret_key = str(os.getenv('MINIO_SECRET_KEY'))
+    minio_bucket_name = str(os.getenv('MINIO_BUCKET_NAME'))
     # connect client
     client = Minio(
         endpoint=minio_endpoint,