# `useChat` "Failed to Parse Stream String" Error

## Issue

I am using [`useChat`](/docs/reference/ai-sdk-ui/use-chat) or [`useCompletion`](/docs/reference/ai-sdk-ui/use-completion), and I am getting a `"Failed to parse stream string. Invalid code"` error. I am using version `3.0.20` or newer of the AI SDK.

## Background

The AI SDK has switched to the stream data protocol in version `3.0.20`.
[`useChat`](/docs/reference/ai-sdk-ui/use-chat) and [`useCompletion`](/docs/reference/ai-sdk-ui/use-completion) expect stream parts that support data, tool calls, etc.
What you see is a failure to parse the stream.
This can be caused by using an older version of the AI SDK in the backend, by providing a text stream using a custom provider, or by using a raw LangChain stream result.

## Solution

You can switch [`useChat`](/docs/reference/ai-sdk-ui/use-chat) and [`useCompletion`](/docs/reference/ai-sdk-ui/use-completion) to raw text stream processing with the [`streamProtocol`](/docs/reference/ai-sdk-ui/use-completion#stream-protocol) parameter.
Set it to `text` as follows:

```tsx
const { messages, append } = useChat({ streamProtocol: 'text' });
```


## Navigation

- [Azure OpenAI Slow to Stream](/v5/docs/troubleshooting/azure-stream-slow)
- [Client-Side Function Calls Not Invoked](/v5/docs/troubleshooting/client-side-function-calls-not-invoked)
- [Server Actions in Client Components](/v5/docs/troubleshooting/server-actions-in-client-components)
- [useChat/useCompletion stream output contains 0:... instead of text](/v5/docs/troubleshooting/strange-stream-output)
- [Streamable UI Errors](/v5/docs/troubleshooting/streamable-ui-errors)
- [Tool Invocation Missing Result Error](/v5/docs/troubleshooting/tool-invocation-missing-result)
- [Streaming Not Working When Deployed](/v5/docs/troubleshooting/streaming-not-working-when-deployed)
- [Streaming Not Working When Proxied](/v5/docs/troubleshooting/streaming-not-working-when-proxied)
- [Getting Timeouts When Deploying on Vercel](/v5/docs/troubleshooting/timeout-on-vercel)
- [Unclosed Streams](/v5/docs/troubleshooting/unclosed-streams)
- [useChat Failed to Parse Stream](/v5/docs/troubleshooting/use-chat-failed-to-parse-stream)
- [Server Action Plain Objects Error](/v5/docs/troubleshooting/client-stream-error)
- [useChat No Response](/v5/docs/troubleshooting/use-chat-tools-no-response)
- [Custom headers, body, and credentials not working with useChat](/v5/docs/troubleshooting/use-chat-custom-request-options)
- [TypeScript performance issues with Zod and AI SDK 5](/v5/docs/troubleshooting/typescript-performance-zod)
- [useChat "An error occurred"](/v5/docs/troubleshooting/use-chat-an-error-occurred)
- [Repeated assistant messages in useChat](/v5/docs/troubleshooting/repeated-assistant-messages)
- [onFinish not called when stream is aborted](/v5/docs/troubleshooting/stream-abort-handling)
- [Tool calling with generateObject and streamObject](/v5/docs/troubleshooting/tool-calling-with-structured-outputs)
- [Abort breaks resumable streams](/v5/docs/troubleshooting/abort-breaks-resumable-streams)
- [streamText fails silently](/v5/docs/troubleshooting/stream-text-not-working)
- [Streaming Status Shows But No Text Appears](/v5/docs/troubleshooting/streaming-status-delay)
- [Stale body values with useChat](/v5/docs/troubleshooting/use-chat-stale-body-data)
- [Type Error with onToolCall](/v5/docs/troubleshooting/ontoolcall-type-narrowing)
- [Unsupported model version error](/v5/docs/troubleshooting/unsupported-model-version)
- [Object generation failed with OpenAI](/v5/docs/troubleshooting/no-object-generated-content-filter)
- [Model is not assignable to type "LanguageModelV1"](/v5/docs/troubleshooting/model-is-not-assignable-to-type)
- [TypeScript error "Cannot find namespace 'JSX'"](/v5/docs/troubleshooting/typescript-cannot-find-namespace-jsx)
- [React error "Maximum update depth exceeded"](/v5/docs/troubleshooting/react-maximum-update-depth-exceeded)
- [Jest: cannot find module '@ai-sdk/rsc'](/v5/docs/troubleshooting/jest-cannot-find-module-ai-rsc)


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