I'm trying to import a PostgreSQL database in Ubuntu. Everything is installed and updated but the problem still presists, any ideas on how to fix this?

I'm trying to import a PostgreSQL database in Ubuntu. Everything is installed and updated but the problem still presists, any ideas on how to fix this?

Login to psql terminal by typing this
sudo -u postgres psql
Enter this command in the psql terminal, exit and try again.
alter role postgres superuser;