bon au moins j'ai compris le problème

Flask/app.py

@@ -159,7 +159,7 @@ def change_password():
 # handle login failed
 @app.errorhandler(401)
 def unauthorized(e):
-    return(redirect("login"))
+    return(redirect("/login"))
 
 
 # callback to reload the user object

Flask/templates/login.html

@@ -3,7 +3,7 @@
 {% block content %}
 
 {%if not current_user.is_authenticated %}
-<form method="post" action="">
+<form method="post" action="/login">
     <table>
         <tr>
             <td class="comlumn-name">password</td>