What causes "no database name" in golang-migrate/migrate?

Provide the full database path in the URL: spanner://projects/myproj/instances/myinst/databases/mydb.

no database name

Error message

no database name

What it means

spanner.ErrNoDatabaseName is returned when the Spanner driver cannot determine the target database. WithInstance/WithConnection return it when Config.DatabaseName is empty, and Open returns it when the spanner:// URL lacks the database path. Spanner migrations are scoped to a specific database, so it is mandatory.

Source

Thrown at database/spanner/spanner.go:37

	"github.com/golang-migrate/migrate/v4"
	"github.com/golang-migrate/migrate/v4/database"

	adminpb "cloud.google.com/go/spanner/admin/database/apiv1/databasepb"
	"google.golang.org/api/iterator"
)

func init() {
	db := Spanner{}
	database.Register("spanner", &db)
}

// DefaultMigrationsTable is used if no custom table is specified
const DefaultMigrationsTable = "SchemaMigrations"

// Driver errors
var (
	ErrNilConfig      = errors.New("no config")
	ErrNoDatabaseName = errors.New("no database name")
	ErrNoSchema       = errors.New("no schema")
	ErrDatabaseDirty  = errors.New("database is dirty")
	ErrLockHeld       = errors.New("unable to obtain lock")
	ErrLockNotHeld    = errors.New("unable to release already released lock")
)

// Config used for a Spanner instance
type Config struct {
	MigrationsTable string
	DatabaseName    string
	// Whether to parse the migration DDL with spansql before
	// running them towards Spanner.
	// Parsing outputs clean DDL statements such as reformatted
	// and void of comments.
	CleanStatements bool
}

// Spanner implements database.Driver for Google Cloud Spanner

View on GitHub (pinned to 01a9643f14)

Solutions

Provide the full database path in the URL: spanner://projects/myproj/instances/myinst/databases/mydb.
Set Config.DatabaseName to the fully qualified 'projects/.../instances/.../databases/...' string when using WithInstance.
Validate the database name/env var is non-empty before constructing the driver.

Example fix

// before
db, err := migrate.New("spanner://projects/p/instances/i", "file://migrations")
// after
db, err := migrate.New("spanner://projects/p/instances/i/databases/mydb", "file://migrations")

Defensive patterns

Strategy: validation

Validate before calling

if cfg == nil || cfg.DatabaseName == "" {
    return fmt.Errorf("spanner database name is required: projects/p/instances/i/databases/d")
}

Type guard

func hasDatabaseName(cfg *spanner.Config) bool { return cfg != nil && cfg.DatabaseName != "" }

Try / catch

if err := m.Up(); err != nil {
    if errors.Is(err, spanner.ErrNoDatabaseName) {
        return fmt.Errorf("check spanner:// URL, must end with /databases/<name>")
    }
    return err
}

Prevention

Store the fully qualified database path in one env var and validate it at startup.
Check the URL has the /databases/<name> segment before calling migrate.New.
Use the admin API or config validation to confirm the database exists.

When it happens

Trigger: WithInstance called with Config{DatabaseName: ""}; Open given a URL like 'spanner://projects/p/instances/i' with no '/databases/D' segment.

Common situations: Partially built spanner:// URLs missing the database component, empty env vars for the project/instance/database path, config assembled from flags where the database name was omitted.

Related errors

AI-assisted analysis of golang-migrate/migrate@01a9643f14 (2026-09-02). Data as JSON: /api/errors/e1274d9c38c96820. Report an issue: GitHub.