What causes "unsupported database driver: %s" in semaphoreui/semaphore?

Set `dialect` to exactly one of: mysql, postgres, sqlite (matching DbDriver constants)

unsupported database driver

Error message

unsupported database driver: %s

What it means

The configured `dialect` value does not match any supported database driver (mysql, postgres, sqlite). The connection-string builder returns 'unsupported database driver: <dialect>' and the caller aborts. Only a specific set of Dialect constants is accepted.

Solutions

Set `dialect` to exactly one of: mysql, postgres, sqlite (matching DbDriver constants)
Check for case sensitivity and typos — the switch is exact-match
If unsure, remove `dialect` entirely so GetDialect infers it from the present mysql/postgres/sqlite section

Example fix

// before (config.json)
{"dialect": "sqlite3", ...}
// after
{"dialect": "sqlite", ...}

Defensive patterns

Strategy: validation

Validate before calling

// whitelist accepted dialects before use
var validDialects = map[string]bool{"mysql": true, "postgres": true, "sqlite": true}
if !validDialects[cfg.Dialect] {
    return fmt.Errorf("dialect %q not in {mysql,postgres,sqlite}", cfg.Dialect)
}

Try / catch

if err := dbSetup(cfg); err != nil {
    log.Printf("bad dialect: %v", err)
    helpers.WriteErrorStatus(w, err.Error(), http.StatusBadRequest)
    return
}

Prevention

Copy dialect values only from official docs (mysql/postgres/sqlite)
Omit `dialect` to let GetDialect infer it from the configured section
Add a config linter step to CI that checks dialect values

When it happens

Trigger: conf.Dialect is set to a misspelled or unknown value (e.g. 'sqlite3', 'postgresq', 'mariadb', 'BOLT') so buildConnectionString reaches `default: err = fmt.Errorf("unsupported database driver: %s", d.Dialect)`.

Common situations: Typo in config.json/config.yml dialect field; docs or tutorials referencing old driver names; copy-paste from another project (e.g. 'sqlite3' from GORM-style configs).

Understand the failure class

Background: Invalid enum value errors: "Unknown type", "Invalid scope", "must be one of" — when a string is not on the library's allowed list — this error's family across 23 libraries.

Related errors

AI-assisted analysis of semaphoreui/semaphore@1774ccb71a (2026-09-07). Data as JSON: /api/errors/9dd53f0af420412d. Report an issue: GitHub.

Appendix: source

Thrown at util/config.go:2074

			connectionString = fmt.Sprintf(
				"postgres://%s:%s@%s/%s",
				dbUser,
				url.QueryEscape(dbPass),
				dbHost,
				dbName)
		} else {
			connectionString = fmt.Sprintf(
				"postgres://%s:%s@%s/postgres",
				dbUser,
				url.QueryEscape(dbPass),
				dbHost)
		}
		connectionString += mapToQueryString(d.Options)
	case DbDriverSQLite:
		connectionString = "file:" + dbHost
		connectionString += mapToQueryString(d.Options)
	default:
		err = fmt.Errorf("unsupported database driver: %s", d.Dialect)
	}
	return
}

// PrintDbInfo prints the database connection information based on the current configuration.
// It retrieves the database dialect and prints the corresponding connection details.
// If the dialect is not found, it panics with an error message.
func (conf *ConfigType) PrintDbInfo() {
	// Get the database dialect
	dialect, err := conf.GetDialect()
	if err != nil {
		panic(err)
	}

	// Print database connection information based on the dialect
	switch dialect {
	case DbDriverMySQL:
		fmt.Printf("MySQL %v@%v %v\n", conf.MySQL.GetUsername(), conf.MySQL.GetHostname(), conf.MySQL.GetDbName())

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