Validating username and password.

[Peter Schober]

* maherterminal1 <maherterminal at gmail.com> [2018-12-02 08:50]:
> I am following a tutorial on youtube on how to set up shibboleth idp
> and I have been able set up shibboleth idp3.2.1, sp and ldap on
> ubuntu 16.04.

You should be using the official documentation from the project, as
this community don't know (or care, really) what someone says in some
random youtube video.
Also, IDP v3.2.1 is obsolete and unsupported. The supported versions
are listed in the documentation.

> the issue I get is when I put the username and password in the IdP login
> page, it open a page with Web login error. so I hit back page. I get this
> error message

What "Web login error" specifically? What is being logged when you
encouter this error condition?

> java.lang.IllegalStateException: You can only resume paused view
> states, and ... is not a view state - programmer error

The wording would suggest a bug in the software.  But I'm not sure
that's even an actual error message (you left out the log level, so
maybe it's just DEBUG which would not be ERROR), but as you say it's
probably the effect of using the back button.

> any hints on how to solve this issue?

You should focus on the authentication error that caused you to use
the back button in the first place (and provide more logs and more
detailed error descriptions), not on the effects of using the back
button.

-peter