n8n-io/n8n · error · TypeORMError

Invalid prefix option given for ${this.entityMetadata.target

Error message

Invalid prefix option given for ${this.entityMetadata.targetName}#${this.propertyName}

What it means

EmbeddedMetadata.buildPartialPrefix handles the @Embedded decorator's `prefix` option. After checking for false and '' (both disable prefix) and a plain string (custom prefix), any other type falls through to `throw new TypeORMError(Invalid prefix option given for ${targetName}#${propertyName})`. The decorator only accepts string | boolean | '' — anything else (number, object, null, array) is invalid.

Source

Thrown at packages/@n8n/typeorm/src/metadata/EmbeddedMetadata.ts:255

	// ---------------------------------------------------------------------

	protected buildPartialPrefix(): string[] {
		// if prefix option was not set or explicitly set to true - default prefix
		if (this.customPrefix === undefined || this.customPrefix === true) {
			return [this.propertyName];
		}

		// if prefix option was set to empty string or explicity set to false - disable prefix
		if (this.customPrefix === '' || this.customPrefix === false) {
			return [];
		}

		// use custom prefix
		if (typeof this.customPrefix === 'string') {
			return [this.customPrefix];
		}

		throw new TypeORMError(
			`Invalid prefix option given for ${this.entityMetadata.targetName}#${this.propertyName}`,
		);
	}

	protected buildPrefix(connection: DataSource): string {
		let prefixes: string[] = [];
		if (this.parentEmbeddedMetadata)
			prefixes.push(this.parentEmbeddedMetadata.buildPrefix(connection));

		prefixes.push(...this.buildPartialPrefix());

		return prefixes.join('_'); // todo: use naming strategy instead of "_"  !!!
	}

	protected buildParentPropertyNames(): string[] {
		return this.parentEmbeddedMetadata
			? this.parentEmbeddedMetadata.buildParentPropertyNames().concat(this.propertyName)
			: [this.propertyName];

View on GitHub (pinned to 5ac6606e81)

Solutions

1. Use a string prefix, false, or '' only: `@Embedded(() => Address, { prefix: 'addr_' })` or `{ prefix: false }`.
2. Validate dynamic prefix values before applying the decorator (coerce to string or boolean).
3. Type the prefix option strictly as `string | boolean` at the configuration boundary.

Example fix

// before
@Embedded(() => Address, { prefix: 0 as any })
address!: Address;

// after - valid prefix type
@Embedded(() => Address, { prefix: 'addr_' })
address!: Address;
// or disable prefixing
@Embedded(() => Address, { prefix: false })
address!: Address;

function asEmbeddedPrefix(v: unknown): string | boolean | undefined {
  if (v === undefined || typeof v === 'string' || typeof v === 'boolean') return v;
  throw new Error(`Invalid @Embedded prefix option: expected string | boolean, got ${typeof v}`);
}
// apply only at decoration time (statically); for dynamic configs, validate before codegen
const prefix = asEmbeddedPrefix(config.userAddressPrefix);

function isValidEmbeddedPrefix(v: unknown): v is string | boolean {
  return typeof v === 'string' || typeof v === 'boolean';
}

When it happens

Trigger: Decorating `@Embedded(() => Address, { prefix: 0 })` or `{ prefix: null }` or `{ prefix: { custom: 'x' } }`; programmatically building embed metadata with a non-conforming prefix; reading prefix from a config file that yielded a non-string/non-boolean; copy-paste of an options object intended for a different decorator.

Common situations: Misunderstanding the prefix option's accepted types; dynamic config-driven embedding with unvalidated prefix values; refactor that changed prefix from string to object without updating all sites; TypeScript `any` letting invalid types through.

Related errors

• Column "${columnName}" was not found in table "${metadata.na
• Column ${propertyPath} was not found in ${metadata.targetNam
• Custom repository ${repository.name} was not found. Did you
• Custom entity repository ${repository.name} cannot inherit R
• Transaction method requires callback in second parameter if

AI-assisted analysis of n8n-io/n8n@5ac6606e81 (2026-08-12). Data as JSON: /api/errors/39dab168c27e1ba5. Report an issue: GitHub.