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

Include the schema in the DSN: user:pass@tcp(host:3306)/mydb

no database name

Error message

no database name

What it means

ErrNoDatabaseName in database/mysql is returned by WithInstance, Open and WithConnection when the database name resolved from the DSN or Config.DatabaseName is empty. MySQL needs the target schema to create/locate the schema_migrations table. The same sentinel also exists in cockroachdb, so the message may originate from either package.

Source

Thrown at database/mysql/mysql.go:35

	"sync/atomic"
	"time"

	"github.com/go-sql-driver/mysql"
	"github.com/golang-migrate/migrate/v4/database"
)

var _ database.Driver = (*Mysql)(nil) // explicit compile time type check

func init() {
	database.Register("mysql", &Mysql{})
}

var DefaultMigrationsTable = "schema_migrations"

var (
	ErrDatabaseDirty    = fmt.Errorf("database is dirty")
	ErrNilConfig        = fmt.Errorf("no config")
	ErrNoDatabaseName   = fmt.Errorf("no database name")
	ErrAppendPEM        = fmt.Errorf("failed to append PEM")
	ErrTLSCertKeyConfig = fmt.Errorf("to use TLS client authentication, both x-tls-cert and x-tls-key must not be empty")
)

type Config struct {
	MigrationsTable  string
	DatabaseName     string
	NoLock           bool
	StatementTimeout time.Duration
}

type Mysql struct {
	// mysql RELEASE_LOCK must be called from the same conn, so
	// just do everything over a single conn anyway.
	conn     *sql.Conn
	db       *sql.DB
	isLocked atomic.Bool

View on GitHub (pinned to 01a9643f14)

Solutions

Include the schema in the DSN: user:pass@tcp(host:3306)/mydb
Set Config.DatabaseName explicitly for WithInstance/WithConnection
Fail fast in deployment config validation when the DB name env var is empty

Example fix

// before
m, err := mysql.Open("user:pass@tcp(localhost:3306)/")
// after
m, err := mysql.Open("user:pass@tcp(localhost:3306)/mydb")

Defensive patterns

Strategy: validation

Validate before calling

if cfg != nil && cfg.DatabaseName == "" {
    return fmt.Errorf("MYSQL_DATABASE must be set or included in the DSN path")
}
// for URL-based Open:
// ensure "tcp(host)/dbname" contains a non-empty db segment

Try / catch

if err != nil {
    if errors.Is(err, mysql.ErrNoDatabaseName) {
        return fmt.Errorf("mysql DSN/config missing database name")
    }
    return err
}

Prevention

Include the schema name in every MySQL DSN
Validate required DB env vars at process startup
Prefer one DSN template so the db segment cannot be dropped

When it happens

Trigger: DSN without a database name (e.g. user:pass@tcp(host)/), Config.DatabaseName == "" with WithInstance/WithConnection, Open on a URL whose path is empty.

Common situations: DSN templates where the DB env var is unset, connection strings copied from tools that use a connect-time database selection, renaming a schema without updating migrate config.

Related errors

AI-assisted analysis of golang-migrate/migrate@01a9643f14 (2026-09-02). Data as JSON: /api/errors/0ab945df3986e675. Report an issue: GitHub.