googleapis/mcp-toolbox · error

failed to create Cassandra session: %w

Error message

failed to create Cassandra session: %w

What it means

cluster.CreateSession() in initCassandraSession failed to establish a session to the Cassandra cluster. This is the underlying connection step; the gocql error is wrapped with %w for direct unwrapping with errors.Is/As.

Source

Thrown at internal/sources/cassandra/cassandra.go:160

			Username: c.Username,
			Password: c.Password,
		}
	}

	// Configure SSL options if any are specified
	if c.CAPath != "" || c.CertPath != "" || c.KeyPath != "" || c.EnableHostVerification {
		cluster.SslOpts = &gocql.SslOptions{
			CaPath:                 c.CAPath,
			CertPath:               c.CertPath,
			KeyPath:                c.KeyPath,
			EnableHostVerification: c.EnableHostVerification,
		}
	}

	// Create session
	session, err := cluster.CreateSession()
	if err != nil {
		return nil, fmt.Errorf("failed to create Cassandra session: %w", err)
	}
	return session, nil
}

View on GitHub (pinned to 8cc6e09de2)

Solutions

1. Verify hosts and port (default 9042) are correct and reachable.
2. Confirm credentials are valid (cqlsh login works).
3. Check ProtoVersion compatibility with the server.
4. Inspect TLS/SSL settings on the cluster config.
5. Use errors.Unwrap to get the root gocql error.

Example fix

// before
cluster.ProtoVersion = 4 // server only supports 3
// after
cluster.ProtoVersion = 3

conn, err := net.DialTimeout("tcp", host+":9042", 3*time.Second)
if err != nil { return fmt.Errorf("cassandra unreachable: %w", err) }
conn.Close()

_, err := cfg.Initialize(ctx, tracer)
if err != nil {
    // retry with backoff; unwrap for gocql root cause
    return fmt.Errorf("session failed: %w", errors.Unwrap(err))
}

When it happens

Trigger: Calling Initialize when gocql cannot dial any host: connection refused, TLS handshake failure, authentication rejected, or protocol version mismatch.

Common situations: Cluster down, wrong port, wrong credentials, TLS misconfiguration, unsupported ProtoVersion, DNS resolution failures.

Understand the failure class

Background: ECONNREFUSED and "connection refused" / "could not connect to server" errors: what they mean and how to fix them — this error's family across 44 libraries.

Related errors

• unable to create session: %v
• unable to create session: %v
• unable to connect successfully: %w
• unable to get AlloyDB connection config: %w
• unable to parse rows: %w

AI-assisted analysis of googleapis/mcp-toolbox@8cc6e09de2 (2026-09-05). Data as JSON: /api/errors/c903b92518a2d086. Report an issue: GitHub.