How to Fix Readablestream Error in Vue

Stumbled on a readablestream error in your Vue application? This common issue has a well-known fix that you can apply in minutes.

Why This Error Occurs

ReadableStream errors in Vue happen when your code attempts to consume a stream that is either locked, already read, or unavailable. Specific scenarios include:

• Calling .getReader() on a stream that's already locked by another reader
• Trying to read response.body during server-side rendering where streams aren't available
• Not releasing the reader lock after consumption, preventing reuse
• Reading the response body twice (e.g., calling both .json() and .text())

Fixing It

// Vue composable for streaming data
import { ref } from "vue";

export function useStream(url) {
  const data = ref("");
  const error = ref(null);
  const loading = ref(false);

  async function startStream() {
    loading.value = true;
    error.value = null;
    data.value = "";

    try {
      const resp = await fetch(url);
      const reader = resp.body?.getReader();
      if (!reader) {
        error.value = "ReadableStream not supported";
        return;
      }

      const decoder = new TextDecoder();
      while (true) {
        const { done, value } = await reader.read();
        if (done) break;
        data.value += decoder.decode(value, { stream: true });
      }
      data.value += decoder.decode(); // flush
    } catch (e) {
      error.value = e.message;
    } finally {
      loading.value = false;
    }
  }

  return { data, error, loading, startStream };
}

Use optional chaining on resp.body and track loading/error state in the composable for a clean component API.

Key Points

• A ReadableStream can only be consumed once — calling .getReader() locks it exclusively
• In SSR environments, response.body may be null — always check before accessing

Use [Bugsly](https://bugsly.dev) to track streaming errors in your Vue application and identify which endpoints and environments cause ReadableStream failures.