criticalPostgreSQLError 08001

PostgreSQL Error 08001: Connection Failure / Unable to Connect

Error Message
FATAL: could not connect to server: Connection refused
	Is the server running on host "localhost" (127.0.0.1) and accepting TCP/IP connections on port 5432?

What is PostgreSQL Error 08001?

PostgreSQL SQLSTATE 08001 indicates the client could not establish a connection to the PostgreSQL server. The connection was actively refused, timed out, or failed during SSL negotiation. This is a network-level or server configuration error, not a SQL logic error.

Common Causes

  • 1

    PostgreSQL server is not running

  • 2

    PostgreSQL is listening on a different port than expected (default: 5432)

  • 3

    Firewall blocking the connection to port 5432

  • 4

    pg_hba.conf is not configured to allow connections from the client host

  • 5

    postgresql.conf listen_addresses does not include the client's interface

  • 6

    SSL certificate mismatch or SSL mode incompatibility

  • 7

    Max connection limit reached (max_connections in postgresql.conf)

Step-by-Step Solutions

1

Verify PostgreSQL is running: pg_ctl status or systemctl status postgresql

2

Check the port: ps aux | grep postgres and netstat -tlnp | grep 5432

3

Check pg_hba.conf and add: host all all 0.0.0.0/0 md5 (then pg_ctl reload)

4

Edit postgresql.conf: listen_addresses = '*' to accept all interfaces (then restart PostgreSQL)

5

Check firewall rules: ufw allow 5432/tcp or the appropriate firewall command

6

Check max connections: SHOW max_connections; and consider PgBouncer for connection pooling

7

Test local socket connection first: psql -U postgres (bypasses network issues)

Prevention Tips

  • Configure pg_hba.conf precisely — whitelist only known IP ranges, not 0.0.0.0/0

  • Use a connection pooler (PgBouncer, pgpool-II) to stay well below max_connections

  • Set up monitoring and alerting for PostgreSQL connection counts

  • Use .pgpass file or PGPASSWORD environment variable, not hardcoded passwords

Frequently Asked Questions

How do I fix PostgreSQL connection refused error?
Step 1: Verify PostgreSQL is running: systemctl status postgresql. Step 2: Check it's listening on the right port: netstat -tlnp | grep postgres. Step 3: Check pg_hba.conf allows your client IP. Step 4: Check postgresql.conf listen_addresses includes your interface. Step 5: Check firewall rules allow port 5432.
What is pg_hba.conf in PostgreSQL?
pg_hba.conf (Host-Based Authentication) controls which hosts can connect, which databases they can access, which users, and what authentication method to use. Each line is a rule: TYPE DATABASE USER ADDRESS METHOD. Common methods: md5 (password), scram-sha-256 (modern password), trust (no password), peer (Unix socket matching).
What is the default PostgreSQL port?
PostgreSQL's default port is 5432. If you changed it in postgresql.conf (port = XXXX), specify it in your connection string: psql -p XXXX or host=localhost port=XXXX in the DSN.

Related Errors

POSTGRESQL 28P01POSTGRESQL 53300POSTGRESQL 08006

Still Stuck?

Ask our AI SQL Assistant or the community — get answers in seconds.

Ask AI Assistant Test in Playground