Can Not Access App: Unauthorized : you must be authenticated to access this page

We have seen some users reporting an issue when trying to download files from an app created thru Flask. 

Below is the error that the user gets:

 "Unauthorized : you must be authenticated to access this page" .

To resolve this issue, check your code for the below line (this could also be listed under POST action):

form action

The above code can cause problems due to routing/reverse proxy setups, and this can be resolved by following these steps:

Change the "form action" code to one of the following:

<form action="#"> or <form action=""> 

If you use "/" as shown below, the url prefix for your app will be stripped, and you'll end up sending your request to <base_domain>/ (this will result in the aforementioned authentication error).

<form action="/">

So, removing "/" from POST request should fix this problem.