googleapis/mcp-toolbox · error

unable to create pool: %w

Error message

unable to create pool: %w

What it means

Wrapped by Firebird Config.Initialize when initFirebirdConnectionPool fails to even open a database/sql pool via the firebirdsql driver. sql.Open only validates the DSN format and driver registration, so this almost always indicates a malformed connection string rather than a network problem.

Source

Thrown at internal/sources/firebird/firebird.go:65

type Config struct {
	Name     string `yaml:"name" validate:"required"`
	Type     string `yaml:"type" validate:"required"`
	Host     string `yaml:"host" validate:"required"`
	Port     string `yaml:"port" validate:"required"`
	User     string `yaml:"user" validate:"required"`
	Password string `yaml:"password" validate:"required"`
	Database string `yaml:"database" validate:"required"`
}

func (r Config) SourceConfigType() string {
	return SourceType
}

func (r Config) Initialize(ctx context.Context, tracer trace.Tracer) (sources.Source, error) {
	pool, err := initFirebirdConnectionPool(ctx, tracer, r.Name, r.Host, r.Port, r.User, r.Password, r.Database)
	if err != nil {
		return nil, fmt.Errorf("unable to create pool: %w", err)
	}

	err = pool.PingContext(ctx)
	if err != nil {
		pool.Close()
		return nil, fmt.Errorf("unable to connect successfully: %w", err)
	}

	s := &Source{
		Config: r,
		Db:     pool,
	}
	return s, nil
}

var _ sources.Source = &Source{}

type Source struct {

View on GitHub (pinned to 8cc6e09de2)

Solutions

1. Check each DSN component is non-empty and properly escaped (URL-encode or escape ':' '@' '/' in user and password)
2. Confirm the database file path is absolute and ends in .fdb for local files, or host:port points at a running Firebird server
3. Ensure _ "github.com/mattn/go-adodb"-style blank import of firebirdsql driver is present (github.com/flygo/fb or mattn/go-firebirdsql per go.mod)
4. Test the DSN manually with a Firebird client (isql) using the same credentials

Example fix

// before
pool, err := initFirebirdConnectionPool(ctx, tracer, r.Name, r.Host, r.Port, r.User, r.Password, r.Database)
if err != nil {
    return nil, fmt.Errorf("unable to create pool: %w", err)
}
// after
if r.Host == "" || r.Database == "" {
    return nil, fmt.Errorf("invalid firebird config: host and database are required")
}
pool, err := initFirebirdConnectionPool(ctx, tracer, r.Name, r.Host, r.Port, r.User, r.Password, r.Database)
if err != nil {
    return nil, fmt.Errorf("unable to create pool: %w", err)
}

// Validate DSN components before Initialize
func validateFirebirdConfig(host, port, user, pass, db string) error {
    if host == "" || port == "" || user == "" || db == "" {
        return errors.New("firebird config: host, port, user and database are required")
    }
    if strings.ContainsAny(user+pass, ":@/") {
        return errors.New("firebird config: user/password contain unescaped DSN characters (: @ /)")
    }
    return nil
}

func isDriverMissing(err error) bool {
    return strings.Contains(err.Error(), "unknown driver")
}

pool, err := initFirebirdConnectionPool(ctx, tracer, name, host, port, user, pass, db)
if err != nil {
    if isDriverMissing(err) {
        return nil, fmt.Errorf("firebirdsql driver not registered; add blank import: %w", err)
    }
    return nil, fmt.Errorf("unable to create pool: %w", err)
}

When it happens

Trigger: Initialize called with a Config whose Name/Host/Port/User/Password/Database produce an invalid DSN (e.g. empty fields, special chars like '@' or ':' in the password breaking user:password@host:port/db format), or the firebirdsql driver not registered.

Common situations: Password containing ':' or '@' unescaped; empty database path (must end in .fdb and include full path for embedded); blank host/port fields from missing config; blank import of the firebirdsql driver missing so sql.Open returns unknown driver.

Related errors

• unable to parse connection uri: %w
• unable to create connection pool: %w
• sql.Open: %w
• sql.Open: %w
• sql.Open: %w

AI-assisted analysis of googleapis/mcp-toolbox@8cc6e09de2 (2026-09-05). Data as JSON: /api/errors/b8017af14404b01a. Report an issue: GitHub.