http://ujwalafossist.blogspot.com/2015/01/operationalerror-fesendauth-no-password.html

Steps suggested to get rid of this error:

1. Stop your OpenERP server.

2. Stop your PostgreSQL server : $ sudo /etc/init.d/postgresql stop

3. Edit your PostgreSQL configuration file pg_hb.conf using nano or gedit editor :
$ sudo gedit /etc/postgresql/9.X/main/pg_hba.conf

4. Now, In the pg_hba.conf file search for the following lines:
# "local" is for Unix domain socket connections only
local         all        all        peer
Here, in above line type of connection used is “peer”, change it to a “trust” i.e.
local         all        all        trust

Now, Save and close the file.
5. After making the above changes to the configuration filepg_hba.conf, Reload and start the PostgreSQL server :
$ sudo /etc/init.d/postgresql restart

This approach works too in Odoo 11 and Ubuntu 16.04 and should resolve the error.

Use PgAdmin (or any other tool or editor) to edit your pg_hba.conf by following the instructions provided in this page