- Plesk for Linux
Unable to configure PostgreSQL in Plesk Onyx on Ubuntu 18.04 with the error below:
PLESK_ERROR: Error: The test connection to the database server has failed:
ERROR: invalid input syntax for type oid: ""
LINE 1: SELECT relname FROM pg_class WHERE relowner = '' AND relkind...
Ubuntu 18.04 comes with PostgreSQL 10 where support for unencrypted passwords was removed. Plesk does not support it currently and this is registered as Plesk bug #PPPM-8775 that is planned to be fixed in future product updates.
For Ubuntu 18.04, there is no workaround at the moment.
Note: in case the same error message occurs on another OS (for example on Ubuntu 16.04 with PostgreSQL 10), then disable custom repositories, remove PostgreSQL via Plesk installer and clean up the packages as described in the following article: PostgreSQL has left over packages after it was removed via Plesk installer