Wildfly - Problems with form based authentication after restart - authentication

Question

We have what I believe to be a pretty standard form based authentication for a web application running on wildfly 8.2.
The authentication works well, except that when we stop&start the server some users are unable to log in again.
I have managed to reproduce one variant of this:
If I open the login page, /xxxx/app, before I restart, and then try to log in after the server is up again, I end up on a blank /xxxx/j_security_check page.
In my logs I can see that the actual authentication is run OK.
If I have understood this j_security_check mechanism properly, it goes something like this:
I access /xxxx/app
Wildfly sees that this url requires authentication. It remembers it and forwards me to login.jsp.
When I submit my login form to the magical j_security_check address it replaces it with the remembered /xxxx/app address.
If this is conceptually correct, I can see that a restart can be troublesome; The web server no longer remembers the /xxxx/app address and doesn't know where to redirect me to.
Does anyone have a workaround for this problem?
Any way to give wildfly a default page to go to after j_security_check?
Edit: I found this one: It is probably the same underlying cause:
Jboss Wildfly 8.1 session timeout on login page
jboss-web.xml:
<jboss-web>
<security-domain>ptsmc</security-domain>
<default-encoding>UTF-8</default-encoding>
</jboss-web>
web.xml:
<servlet-mapping>
<servlet-name>main</servlet-name>
<url-pattern>/app/*</url-pattern>
</servlet-mapping>
<!-- -->
<welcome-file-list>
<welcome-file>index.html</welcome-file>
</welcome-file-list>
<security-constraint>
<display-name>ptsmc</display-name>
<web-resource-collection>
<web-resource-name>ptsmc</web-resource-name>
<url-pattern>/app/*</url-pattern>
</web-resource-collection>
<auth-constraint>
<role-name>WEB</role-name>
</auth-constraint>
<user-data-constraint>
<transport-guarantee>NONE</transport-guarantee>
</user-data-constraint>
</security-constraint>
<login-config>
<auth-method>FORM</auth-method>
<form-login-config>
<form-login-page>/login.jsp</form-login-page>
<form-error-page>/error.html</form-error-page>
</form-login-config>
</login-config>
<security-role>
<description>Users must have this role to be granted access to Application</description>
<role-name>WEB</role-name>
</security-role>
login.jsp:
<form name="login_form" method="POST" action="<%=response.encodeURL(request.getContextPath() + "/j_security_check")%>">
<table>
<tr><td>User id:</td><td><input type=text name=j_username autofocus onblur="this.value = this.value.toUpperCase();"></td></tr>
<tr><td>Password:</td><td><input type=password name=j_password></td></tr>
<tr><td> </td><td><input type=submit value="Submit"></td></tr>
</table>
</form>