---
title: AI_InvalidPromptError
description: Learn how to fix AI_InvalidPromptError
---

# AI_InvalidPromptError

This error occurs when the prompt provided is invalid.

## Potential Causes

### System Messages in `prompt` or `messages`

AI SDK functions reject system messages in the `prompt` or `messages` fields to reduce the risk of prompt injection.
Pass system instructions with the `instructions` option instead:

```typescript
import { generateText } from 'ai';

const result = await generateText({
  // ...
  instructions: 'You are a helpful assistant.',
  messages,
});
```

If the system messages come from a trusted source, you can allow them with `allowSystemInMessages: true`.

### Empty Messages

The `messages` array (or a `prompt` given as an array) must contain at least one message.

### Provider-Specific Prompt Requirements

Some providers throw this error when a prompt can't be expressed for their API,
for example when an assistant prefix message isn't the final message, or when a part combines options the provider doesn't support.
The error message describes the provider requirement that wasn't met.

<Note>
  AI SDK functions do not validate the shape of `ModelMessage` objects at
  runtime. If your messages come from an untrusted source, validate them before
  passing them to an AI SDK function. See
  [`ModelMessage`](/docs/reference/ai-sdk-core/model-message).
</Note>

## Properties

- `prompt`: The invalid prompt value
- `message`: The error message (required in constructor)
- `cause`: The cause of the error (optional)

## Checking for this Error

You can check if an error is an instance of `AI_InvalidPromptError` using:

```typescript
import { InvalidPromptError } from 'ai';

if (InvalidPromptError.isInstance(error)) {
  // Handle the error
}
```