I have a Postgres 9.6 installation on a developer pc and a restore seems to have failed. Even after reinstalling (remove Postgres and PgAdmin completely, incl. database and
Found solution: This problem is related to the pgadmin.db. Just remove the file and the error is gone (but you also have to reenter all passwords etc.). The problem is that this file is not removed when uninstalling postgres/pgadmin. It can be found in