Migration guide

Lists the breaking changes that you need to address to upgrade from v0.x to v1.0.


To update, change your package.json entry for sveltekit-superforms to ^1.0.0:

  "devDependencies": {
    "sveltekit-superforms": "^1.0.0"

(If you’re using Svelte 4, you’ll need at least version ^1.1.2 of Superforms.)

The guide is written with the affected methods in the headlines, so you can scan through this page and apply the changes if you’re using them in your code.


For type safety reasons, you cannot pass null, undefined, or arbitrary data to superForm anymore. Instead, you should be using superValidate to get the initial form object, by returning { form } from a load function and passing it to superForm.

Not doing this will result in the following warning:

No form data sent to superForm, schema type safety cannot be guaranteed. Also, no constraints will exist for the form.
Set the warnings.noValidationAndConstraints option to false to disable this warning.

When this happens, you need to check the call to superForm and apply the above fix.

In client-only scenarios, especially in SPA’s, you must use superValidate or superValidateSync before calling superForm. Read more on the SPA page about this.

valid, empty, firstError

The $valid, $empty, and $firstError stores are removed from the client; they weren’t that useful. $allErrors can be used instead, together with the new $posted store (which shows if the form has been previously posted or not).

empty is removed from the object returned from superValidate, which type was previously called Validation but is now called SuperValidated.


The setError function works as before, except that you must use an empty string instead of null for form-level errors.

Note, however, that setError conflicts with client-side validation, the errors will be removed when a Zod schema is used for validation. Therefore, rely on the schema for most validation, if you’re using it client-side.

const schema = z
    password: z.string().min(8),
    confirmPassword: z.string()
  .refine((data) => password == confirmPassword, `Passwords doesn't match.`);

The above error set in refine will be available on the client as $errors._errors as before, and will be automatically removed (or added) during client-side validation.

If you’d like a form-level message to persist, using message instead of setError will persist it until the next form submission:

const form = await superValidate(request, zod(schema));

if (!form.valid) return fail(400, { form });

if (form.data.password != form.data.confirmPassword) {
  // Stays until form is posted again, regardless of client-side validation
  return message(form, `Passwords doesn't match`, { status: 400 });

Finally, the status option for setError (and message) must be in the 400-599 range.

setError (again), validate, proxy functions

FieldPath is gone - the above methods are now using a string accessor like tags[2].id instead of the previous array syntax ['tags', 2, 'id'].

const { form, enhance, validate } = superForm(data.form)

- validate(['tags', i, 'name'], { update: false });
+ validate(`tags[${i}].name`, { update: false });

This also applies to generic components. The types have been simplified, so you should change them to this, also described on the componentization page:

<script lang="ts">
  import type { z, AnyZodObject } from 'zod';
  import type { ZodValidation, FormPathLeaves } from 'sveltekit-superforms';
  import { formFieldProxy, type SuperForm } from 'sveltekit-superforms/client';

  type T = $$Generic<AnyZodObject>;

  export let form: SuperForm<ZodValidation<T>, unknown>;
  export let field: FormPathLeaves<z.infer<T>>;

  const { value, errors, constraints } = formFieldProxy(form, field);

Also note that arrays and objects cannot be used in formFieldProxy. So if your schema is defined as:

import { formFieldProxy } from 'sveltekit-superforms/client';

const schema = z.object({
  tags: z
      id: z.number(),
      name: z.string().min(1)

const formData = superForm(data.form);

// This won't work
const tags = formFieldProxy(formData, 'tags');

// Not this either
const tag = formFieldProxy(formData, 'tags[0]');

// But this will work since it's a field at the "end" of the schema
const tagName = formFieldProxy(formData, 'tags[0].name');

This only applies to formFieldProxy, since it maps to errors and constraints as well as the form. If you want to proxy just a form value, fieldProxy will work with any part of the schema.

import { fieldProxy } from 'sveltekit-superforms/client';

const { form } = superForm(data.form);
const tags = fieldProxy(form, 'tags');


The signature for allErrors has changed, to make it easier to group related messages:

- { path: string[]; message: string[] }
+ { path: string; messages: string[] }

The path follows the same format as the above-described string accessor path. If you want to display all messages grouped:

{#if $allErrors.length}
    {#each $allErrors as error}
        {error.messages.join('. ')}.

Or as before, separate for each error:

{#if $allErrors.length}
    {#each $allErrors as error}
      {#each error.messages as message}


The undocumented defaultData function is now called defaultValues. You can use this to get the default values for a schema.

- import { defaultData } from 'sveltekit-superforms/server`
+ import { defaultValues } from 'sveltekit-superforms/server`

See the API for documentation.

message, setMessage

The valid option is removed from message/setMessage; any status >= 400 will return a fail. As with setError, the status code must be in the 400-599 range.


The virtually unused meta store, which containted some basic metadata about the schema, has been removed. Use the Zod schema directly instead for reflection.

Client options

The following superForm options have changed:


Resetting the form now works without use:enhance and without JavaScript! Just set the resetForm option to true.

If you have used the function version of resetForm, () => boolean, it is now synchronous.


The default errorSelector is now [aria-invalid="true"],[data-invalid], so if you want to be more accessibility-friendly:

-  data-invalid={$errors.name}
+  aria-invalid={$errors.name ? 'true' : undefined}

Server options

The following superValidate options have changed:


noErrors is removed from the options. Use errors instead to determine if errors should be added or not to the validation.

// Add errors to an empty form
const form = await superValidate(zod(schema), { errors: true });

The 1.0 release notes have a full list of changes, and as usual, let me know on Github or Discord if something is unclear or not working.

Found a typo or an inconsistency? Make a quick correction here!