When the server changes the session management key, for any reason, do not inform the client about the error; expires session instead

Currently if the server changes its session management, the client will always get an error response, needing to have its cookies manually deleted (which is not simple even for me as an user :-() to be able to use the system again.

This MR expires the cookies automatically on the server side, forcing the user to login/register again, instead.