vercel/ai · error · InvalidArgumentError

Invalid argument for parameter schemaName: Schema name is no

Error message

Invalid argument for parameter schemaName: Schema name is not supported for no-schema output.

What it means

schemaName names the schema (used e.g. as the OpenAI function/structured-output name). For output: 'no-schema' no schema exists, so passing schemaName is contradictory and the library throws InvalidArgumentError.

Source

Thrown at packages/ai/src/generate-object/validate-object-generation-input.ts:49

  if (output === 'no-schema') {
    if (schema != null) {
      throw new InvalidArgumentError({
        parameter: 'schema',
        value: schema,
        message: 'Schema is not supported for no-schema output.',
      });
    }

    if (schemaDescription != null) {
      throw new InvalidArgumentError({
        parameter: 'schemaDescription',
        value: schemaDescription,
        message: 'Schema description is not supported for no-schema output.',
      });
    }

    if (schemaName != null) {
      throw new InvalidArgumentError({
        parameter: 'schemaName',
        value: schemaName,
        message: 'Schema name is not supported for no-schema output.',
      });
    }

    if (enumValues != null) {
      throw new InvalidArgumentError({
        parameter: 'enumValues',
        value: enumValues,
        message: 'Enum values are not supported for no-schema output.',
      });
    }
  }

  if (output === 'object') {
    if (schema == null) {
      throw new InvalidArgumentError({

View on GitHub (pinned to 69428b1f8b)

Solutions

Remove schemaName from the call when using output: 'no-schema'.
If you need a named structured output, use output: 'object' with schema and schemaName.
Centralize no-schema calls in a helper that omits schema-related options entirely.

Example fix

// before
generateObject({ model, output: 'no-schema', schemaName: 'UserObject', prompt });
// after
generateObject({ model, output: 'no-schema', prompt });

Defensive patterns

Strategy: validation

Validate before calling

if (opts.output === 'no-schema' && opts.schemaName != null) {
  throw new Error("schemaName must be omitted when output is 'no-schema'");
}

Type guard

function isCleanNoSchemaOptions(opts) {
  return opts.output === 'no-schema'
    && opts.schema == null
    && opts.schemaName == null
    && opts.schemaDescription == null;
}

Try / catch

try {
  await generateObject(opts);
} catch (error) {
  if (InvalidArgumentError.isInstance(error) && error.parameter === 'schemaName') {
    const { schemaName, ...rest } = opts;
    return generateObject(rest);
  }
  throw error;
}

Prevention

Only set schemaName together with a schema for object/array output.
Write a small options sanitizer for no-schema calls.
Lint your call sites for output: 'no-schema' combined with schema* options.

When it happens

Trigger: Calling generateObject({ model, output: 'no-schema', schemaName: 'MyObject', prompt }) or streamObject with schemaName set alongside no-schema output.

Common situations: Shared request-builder helper that always sets schemaName; migrating calls between object and no-schema modes without pruning schema-related options; template code copied from a schema-based example.

Related errors

AI-assisted analysis of vercel/ai@69428b1f8b (2026-08-30). Data as JSON: /api/errors/0d406dda43cc0a00. Report an issue: GitHub.