The installation of OpenACS (HEAD) under PostgreSQL 11 fails without a small change in acs-kernel that I have just committed [1]. Beside that it seems to work okay – I am running a dev instance for some weeks already.
[1] http://cvs.openacs.org/browse/OpenACS/openacs-4/packages/acs-kernel/sql/postgresql/postgresql.sql?r1=1.51&r2=1.52
