---
id: warnings
title: Warnings
---

This is a list of warning output from NextAuth.js.

All warnings indicate things which you should take a look at, but do not inhibit normal operation.

---

## Client

#### NEXTAUTH_URL

Environment variable `NEXTAUTH_URL` missing. Please set it in your `.env` file.

---

## Server

These warnings are displayed on the terminal.

#### JWT_AUTO_GENERATED_SIGNING_KEY

To remedy this warning, you can either:

**Option 1**: Pass a pre-regenerated Private Key (and, optionally a Public Key) in the jwt options.

```js title="/pages/api/auth/[...nextauth].js"
jwt: {
  signingKey: process.env.JWT_SIGNING_PRIVATE_KEY,

  // You can also specify a public key for verification if using public/private key (but private only is fine)
  // verificationKey: process.env.JWT_SIGNING_PUBLIC_KEY,

  // If you want to use some key format other than HS512 you can specify custom options to use
  // when verifying (note: verificationOptions should include a value for maxTokenAge as well).
  // verificationOptions = {
  //   maxTokenAge: `${maxAge}s`, // e.g. `${30 * 24 * 60 * 60}s` = 30 days
  //   algorithms: ['HS512']
  // },
}
```

You can use [node-jose-tools](https://www.npmjs.com/package/node-jose-tools) to generate keys on the command line and set them as environment variables, i.e. `jose newkey -s 256 -t oct -a HS512`.

**Option 2**: Specify custom encode/decode functions on the jwt object. This gives you complete control over signing / verification / etc.

#### JWT_AUTO_GENERATED_ENCRYPTION_KEY

#### SIGNIN_CALLBACK_REJECT_REDIRECT

You returned something in the `signIn` callback, that is being deprecated.

You probably had something similar in the callback:

```js
return Promise.reject("/some/url")
```

or

```js
throw "/some/url"
```

To remedy this, simply return the url instead:

```js
return "/some/url"
```

#### STATE_OPTION_DEPRECATION

You provided `state: true` or `state: false` as a provider option. This is being deprecated in a later release in favour of `protection: "state"` and `protection: "none"` respectively. To remedy this warning:

- If you use `state: true`, just simply remove it. The default is `protection: "state"` already..
- If you use `state: false`, set `protection: "none"`.