We’ve found a problem with PostgreSQL queries in our v2.3.0 release on Thursday. This resulted in an error in Icinga Web 2 (see bug notes), when clicking host names or service names in any list view. The problem was caused by how PostgreSQL handles GROUPBY clauses different to MySQL.
As usual you can get the packages here or check out version 2.3.1 on Github.
See the v2.3.1 changelog.