Error Handling

Learn how to handle errors and warnings in AI SDK UI applications with error states, callbacks, and custom error messages.

Error Handling and Warnings

Warnings

The AI SDK shows warnings when something might not work as expected. These warnings help you fix problems before they cause errors.

When Warnings Appear

Warnings are shown in the browser console when:

• Unsupported features: You use a feature or setting that is not supported by the AI model (e.g., certain options or parameters).
• Compatibility warnings: A feature is used in a compatibility mode, which might work differently or less optimally than intended.
• Other warnings: The AI model reports another type of issue, such as general problems or advisory messages.

Warning Messages

All warnings start with “AI SDK Warning:” so you can easily find them. For example:

AI SDK Warning: The feature "temperature" is not supported by this model

Turning Off Warnings

By default, warnings are shown in the console. You can control this behavior:

Turn Off All Warnings

Set a global variable to turn off warnings completely:

globalThis.AI_SDK_LOG_WARNINGS = false;

Custom Warning Handler

You can also provide your own function to handle warnings. It receives provider id, model id, and a list of warnings.

globalThis.AI_SDK_LOG_WARNINGS = ({ warnings, provider, model }) => {
  // Handle warnings your own way
};

Error Handling

Error Helper Object

Each AI SDK UI hook also returns an error object that you can use to render the error in your UI. You can use the error object to show an error message, disable the submit button, or show a retry button.

We recommend showing a generic error message to the user, such as “Something went wrong.” This is a good practice to avoid leaking information from the server.

'use client';

import { useChat } from '@ai-sdk/react';
import { useState } from 'react';

export default function Chat() {
  const [input, setInput] = useState('');
  const { messages, sendMessage, error, regenerate } = useChat();

  const handleSubmit = (e: React.FormEvent) => {
    e.preventDefault();
    sendMessage({ text: input });
    setInput('');
  };

  return (
    <div>
      {messages.map(m => (
        <div key={m.id}>
          {m.role}:{' '}
          {m.parts
            .filter(part => part.type === 'text')
            .map(part => part.text)
            .join('')}
        </div>
      ))}

      {error && (
        <>
          <div>An error occurred.</div>
          <button type="button" onClick={() => regenerate()}>
            Retry
          </button>
        </>
      )}

      <form onSubmit={handleSubmit}>
        <input
          value={input}
          onChange={e => setInput(e.target.value)}
          disabled={error != null}
        />
      </form>
    </div>
  );
}

Alternative: replace last message

Alternatively you can write a custom submit handler that replaces the last message when an error is present.

'use client';

import { useChat } from '@ai-sdk/react';
import { useState } from 'react';

export default function Chat() {
  const [input, setInput] = useState('');
  const { sendMessage, error, messages, setMessages } = useChat();

  function customSubmit(event: React.FormEvent<HTMLFormElement>) {
    event.preventDefault();

    if (error != null) {
      setMessages(messages.slice(0, -1)); // remove last message
    }

    sendMessage({ text: input });
    setInput('');
  }

  return (
    <div>
      {messages.map(m => (
        <div key={m.id}>
          {m.role}:{' '}
          {m.parts
            .filter(part => part.type === 'text')
            .map(part => part.text)
            .join('')}
        </div>
      ))}

      {error && <div>An error occurred.</div>}

      <form onSubmit={customSubmit}>
        <input value={input} onChange={e => setInput(e.target.value)} />
      </form>
    </div>
  );
}

Error Handling Callback

Errors can be processed by passing an onError callback function as an option to the useChat or useCompletion hooks. The callback function receives an error object as an argument.

import { useChat } from '@ai-sdk/react';

export default function Page() {
  const {
    /* ... */
  } = useChat({
    // handle error:
    onError: error => {
      console.error(error);
    },
  });
}

Injecting Errors for Testing

You might want to create errors for testing. You can easily do so by throwing an error in your route handler:

export async function POST(req: Request) {
  throw new Error('This is a test error');
}