So, the error screenshot looks like the attached one.
It appears when I have an error during the SAML communication (ex: wrong metadata, missing configurations). It is raised by `Shibboleth`.
In my `message.properties` I have the corresponding setup part:
idp.logo = /images/dummylogo.png
idp.logo.alt-text = My Company LTD.
idp.logo.target.url = http://www.mycompanyltd.com