When working with pgAdmin's query tool, you might encounter this frustrating connection error that prevents you from executing queries. The error typically appears when:

• Trying to establish a new connection
• After a period of inactivity
• When network conditions change

Let's examine when this error most frequently occurs:

# Sample connection string that might trigger this issue
conn = psycopg2.connect(
    host="localhost",
    database="mydb",
    user="postgres",
    password="secret",
    sslmode="require"
)

The error suggests the TCP socket connection was terminated before SSL negotiation could complete. This often happens due to:

• Firewall rules blocking the port
• SSL certificate misconfiguration
• Server-side timeout settings

First verify your PostgreSQL server's SSL configuration in postgresql.conf:

# Minimum SSL configuration
ssl = on
ssl_cert_file = 'server.crt'
ssl_key_file = 'server.key'
ssl_ca_file = 'root.crt'
# Connection timeout settings
tcp_keepalives_idle = 60
tcp_keepalives_interval = 10

Try these pgAdmin-specific fixes:

1. Clear the query tool cache: File → Reset Layout
2. Modify connection properties:
   • Set SSL mode to "prefer" instead of "require"
   • Increase connection timeout values

Use these commands to test basic connectivity:

# Test port accessibility
telnet your-db-host 5432
# Verify certificate chain
openssl s_client -connect your-db-host:5432 -showcerts

For persistent applications, consider implementing connection pooling:

from psycopg2.pool import SimpleConnectionPool
pool = SimpleConnectionPool(
    minconn=1,
    maxconn=10,
    host="localhost",
    database="mydb",
    user="postgres",
    password="secret",
    sslmode="verify-full"
)

This approach handles connection drops more gracefully than direct connections.

---

If you're seeing the "could not send SSL negotiation packet: Socket is not connected" error when opening pgAdmin's query tool, you're not alone. This typically happens when there's an interruption in the secure connection between pgAdmin and PostgreSQL server.

The error frequently appears in these situations:

• After network configuration changes
• When the PostgreSQL service restarts unexpectedly
• During VPN connection drops
• After system sleep/wake cycles

Before diving deep, try these quick solutions:

# Restart pgAdmin service
sudo systemctl restart pgadmin4

# Check PostgreSQL service status
sudo systemctl status postgresql

If that doesn't work, verify your connection settings:

# Example connection string verification
psql -h your_host -p 5432 -U your_user -d your_db -W

The root cause often lies in SSL misconfiguration. Check your postgresql.conf:

# Minimum SSL configuration
ssl = on
ssl_cert_file = '/path/to/server.crt'
ssl_key_file = '/path/to/server.key'
ssl_ca_file = '/path/to/root.crt'

Use these commands to diagnose network issues:

# Test basic connectivity
telnet your_postgres_host 5432

# Verify SSL handshake
openssl s_client -connect your_postgres_host:5432 -starttls postgres

Sometimes the issue is pgAdmin-specific. Try these steps:

1. Clear pgAdmin's cache directory
2. Create a new server connection
3. Adjust connection timeout settings

If you're using connection pooling (like PgBouncer), ensure proper SSL passthrough:

[databases]
yourdb = host=your_postgres_host dbname=yourdb

[pgbouncer]
listen_port = 6432
auth_type = trust
server_tls_sslmode = require

After making changes, verify with:

SELECT * FROM pg_stat_ssl WHERE pid = pg_backend_pid();

This should show your current SSL connection details if everything is working properly.