Update flask_app.py

flask_app.py

@@ -12,7 +12,8 @@ ALLOWED_EXTENSIONS = {'png', 'jpg', 'jpeg'}
 
 app = Flask(__name__)
 app.config["SESSION_PERMANENT"] = False
-app.config["SESSION_TYPE"] = "null"
+app.config["SESSION_TYPE"] = "filesystem
+"
 app.config['UPLOAD_FOLDER'] = UPLOAD_FOLDER
 
 Session(app)