Error on postgresql ubuntu

i am getting this error

ERROR: Main method error - ERROR: permission denied for schema public
  Position: 14 - PSQLException (... < DatabaseModule:95 < <gener:-1 < *:-1 < ... < Main:126 < ...)

my command

cat > /opt/traccar/conf/traccar.xml << EOF
<?xml version='1.0' encoding='UTF-8'?>

<!DOCTYPE properties SYSTEM 'http://java.sun.com/dtd/properties.dtd'>

<properties>

    <entry key="config.default">./conf/default.xml</entry>

<entry key='database.driver'>org.postgresql.Driver</entry>
<entry key='database.url'>jdbc:postgresql://127.0.0.1:5432/traccar</entry>
<entry key='database.user'>user</entry>
<entry key='database.password'>password</entry>

</properties>
EOF

sudo -u postgres psql
CREATE DATABASE traccar;
CREATE USER user WITH ENCRYPTED PASSWORD 'password';
GRANT ALL PRIVILEGES ON DATABASE traccar TO user;
GRANT USAGE ON schema public TO user;

Can anybody user postgresql ubuntu?
help me out.

The error is coming from Postgres, so seems like there's some problem with your permission configuration.

As Anton says, looks like a permission issue Have you given the traccar user full permissions on the traccar database?