If you are experiencing an error message similar to "psql: could not connect to server: Connection refused" when attempting to connect to a PostgreSQL database server, it could be due to a problem with the PostgreSQL server, the network configuration, or the connection parameters.
Here are some possible solutions to this issue:
systemctl command to check the status of the PostgreSQL service. For example:# systemctl status postgresql
If the PostgreSQL server is not running, start it using the systemctl command. For example:
# systemctl start postgresql
Check the PostgreSQL configuration to make sure that the server is listening on the correct IP address and port. The listen_addresses and port parameters in the postgresql.conf configuration file specify the IP address and port that the server will listen on for incoming connections. Make sure that these parameters are correctly configured.
Check the firewall configuration to make sure that the PostgreSQL port is not being blocked. If the server is behind a firewall, make sure that the firewall is configured to allow incoming connections on the PostgreSQL port.
Check the connection parameters to make sure that you are using the correct hostname, port, and username when connecting to the PostgreSQL server. You can use the -h, -p, and -U options to specify the hostname, port, and username, respectively. For example:
# psql -h hostname -p port -U username
If none of these solutions resolves the issue, you may need to consult the PostgreSQL documentation and online resources for further troubleshooting guidance. It's important to note that troubleshooting issues with PostgreSQL can be complex and may require a good understanding of the PostgreSQL configuration and the underlying system.