Hi Totophe,
Thank you for the response. I apologize for the delay in responding, I have been out of the office this week.
I am currently running Ilias 5.0.4 with Debian Wheezy and mySQL. I tried to replicate your error without success. I reviewed your error logs and looked at the code that is issuing the error and don't see any problems with it. The query itself is from the getObjectReferenceOfRole method in Services/AccessControl/classes/class.ilRbacReview.php
Debian Jessie: I doubt this is the issue since it is the OS and a web server running. I haven't done much research into version 8 yet, but I just can't see this being the problem.
Postgres: This could be the problem here. As outlined in the install documentation (http://www.ilias.de/docu/goto.php?target=lm_367&client_id=docu), Postgres is considered experimental.
Quotation from above link:
"Experimental, current versions of PostgreSQL should work but are not tested. Contact info@ilias.de, if you would like to use ILIAS on PostgreSQL and are willing to help us testing the platform."
At this point, I would recommend reaching out to the contact listed above and ask them for direction into this error. I am not sure why the query SELECT parent ref FROM rbac_fa WHERE rol_id=? AND assign='y' would fail, but according to your logs, there is a syntax error somehow in there. It is very possible that the parameter $a_role_id is not defined, but in the comments for that method, they aren't checking to see if the role was deleted. If you have created a role and deleted it, this may be the cause of your error (although I can't replicate that either).
Regards,
Adam