---
title: Troubleshooting
description: "Solutions for common Hyperframes issues."
---

If your issue is about a specific coding mistake (animations not working, video cutting off early), see [Common Mistakes](/guides/common-mistakes) first. This page covers environment, tooling, and rendering issues.

<AccordionGroup>
  <Accordion title='"No composition found"'>
    Your directory needs an `index.html` with a valid [composition](/concepts/compositions). The root element must have a [`data-composition-id`](/concepts/data-attributes#composition-attributes) attribute.

    **Fix:** Run `npx hyperframes init` to create a composition from an [example](/examples), or verify your `index.html` has the correct structure:

    ```html index.html
    <div id="root" data-composition-id="my-video"
         data-width="1920" data-height="1080">
      <!-- elements here -->
    </div>
    ```
  </Accordion>

  <Accordion title='"FFmpeg not found"'>
    Local [rendering](/guides/rendering) requires FFmpeg installed on your system. Install it for your platform:

    <CodeGroup>
    ```bash macOS
    brew install ffmpeg
    ```

    ```bash Ubuntu/Debian
    sudo apt install ffmpeg
    ```

    ```bash Windows
    # Download from https://ffmpeg.org/download.html
    # Add the bin directory to your PATH
    ```

    ```bash Verify installation
    ffmpeg -version
    ```
    </CodeGroup>

    After installing, run `npx hyperframes doctor` to verify the CLI can find it.

    <Tip>
      If you cannot install FFmpeg, use [Docker mode](/guides/rendering) instead — it bundles FFmpeg inside the container: `npx hyperframes render --docker --output output.mp4`
    </Tip>
  </Accordion>

  <Accordion title="Lint errors">
    Run `npx hyperframes lint` to check for common structural issues (see [CLI: lint](/packages/cli#lint)):

    | Error | Meaning |
    |-------|---------|
    | Missing `data-composition-id` | Root element needs this attribute. See [Compositions](/concepts/compositions). |
    | Missing `class="clip"` | Timed visible elements need this class. See [Data Attributes](/concepts/data-attributes#element-visibility). |
    | Overlapping timelines | Clips on the same [`data-track-index`](/concepts/data-attributes#timing-attributes) cannot overlap in time. |
    | Unmuted video elements | Video elements should be `muted` unless `data-has-audio="true"` is set. |
    | Deprecated attribute names | `data-layer` and `data-end` have been replaced. Check the [HTML Schema Reference](/reference/html-schema). |
  </Accordion>

  <Accordion title="Preview not updating">
    Make sure you are editing the `index.html` in the project directory. The [preview server](/packages/cli#preview) watches for file changes and auto-reloads.

    If changes still do not appear:

    1. Check the terminal for errors from the preview server
    2. Stop and restart `npx hyperframes preview`
    3. Hard-refresh the browser: **Ctrl+Shift+R** (Windows/Linux) or **Cmd+Shift+R** (macOS)
    4. Clear the browser cache if CSS changes are not reflected
  </Accordion>

  <Accordion title="Preview stutters or plays at a low frame rate">
    **Symptom:** Preview playback is jerky or skips frames, but the rendered mp4 looks fine.

    **Cause:** Individual frames are taking longer than 16-33ms to paint. Render hides this (it captures frames one at a time), preview does not.

    **Common culprits, most to least frequent:**

    - Stacked `backdrop-filter: blur()` layers, especially at radii above 32px
    - Source images at very high resolution (above 4K) displayed in small regions
    - `filter: blur()` or `filter: drop-shadow()` on large elements
    - Many elements with `box-shadow` or `text-shadow` that also animate

    **First thing to check:** does the stutter happen only during specific scenes, or throughout? Scene-specific stutter usually points at an element, often a blur overlay, that becomes visible in that scene.

    **How to diagnose:** open Chrome DevTools, switch to the Performance tab, record a few seconds of playback, and look for long tasks labeled "Composite Layers" or "Paint". See [Performance: Measuring a slow composition](/guides/performance#measuring-a-slow-composition) for the full walkthrough.

    **Temporary workaround:** render to mp4 and watch the output. Render is accurate regardless of per-frame cost.

    ```bash Terminal
    npx hyperframes render --quality draft --output preview.mp4
    ```

    See [Performance](/guides/performance) for the full guide on expensive CSS patterns and how to fix them.
  </Accordion>

  <Accordion title="Render looks different from preview">
    Use `--docker` mode for [deterministic output](/concepts/determinism). Local renders may differ due to:

    - **Font availability** — different fonts on different platforms cause text reflow
    - **Chrome version** — local Chromium vs. Docker's pinned version can render slightly differently
    - **System-specific rendering** — GPU compositing, subpixel antialiasing, etc.

    ```bash Terminal
    npx hyperframes render --docker --output output.mp4
    ```

    See [Rendering: When to Use Each Mode](/guides/rendering#when-to-use-each-mode) for guidance on choosing between local and Docker rendering.
  </Accordion>

  <Accordion title="Docker mode fails to start">
    Verify Docker is installed and the daemon is running:

    ```bash Terminal
    docker info
    ```

    Common issues:
    - **Docker not running:** Start Docker Desktop or the Docker daemon
    - **Permission denied:** Add your user to the `docker` group (`sudo usermod -aG docker $USER`) and restart your shell
    - **Image pull fails:** Check your internet connection; the first render downloads the Hyperframes Docker image
  </Accordion>

  <Accordion title="Render is slow">
    Try these optimizations:

    1. Use `--quality draft` during development for faster encoding
    2. Run `npx hyperframes benchmark` to find the optimal worker count for your system
    3. Local Chrome/WebGL GPU capture is enabled automatically; compare with `--no-browser-gpu` if troubleshooting
    4. Use `--gpu` for hardware-accelerated encoding (local mode only)
    5. Reduce `--fps` to 24 if 30fps is not needed
    6. Check that your composition does not have unnecessary elements or overly complex animations

    See [Rendering: Options](/guides/rendering#options) for all available flags.
  </Accordion>

  <Accordion title="Video asset plays black in preview but renders fine (HEVC/H.265)">
    Rendering decodes video assets with FFmpeg, so HEVC (H.265) inputs render correctly on every platform. Live preview is different: `preview`, `play`, Studio, and published player pages play the file in your browser, and not every browser decodes HEVC (Chrome 107+, Edge, and Safari do on most modern hardware; Firefox does not). This is now self-healing: preview detects an undecodable asset and automatically swaps in a cached H.264 proxy, so this should no longer show as a persistent black frame.

    If a hostile asset is still stuck black in preview:

    1. Confirm auto-proxying is not disabled: no `--no-proxy` flag, and `media.autoProxy` is not `false` in `hyperframes.json`.
    2. Run `npx hyperframes doctor` to confirm ffmpeg/ffprobe are installed; the proxy transcode needs both.
    3. Run `npx hyperframes lint --verbose`: the info-level `hevc_preview_codec` finding names every affected asset.

    See [Rendering: Input Video Codecs](/guides/rendering#input-video-codecs).
  </Accordion>
</AccordionGroup>

## System Diagnostics

Run `npx hyperframes doctor` to check your environment:

```bash Terminal
npx hyperframes doctor
```

This checks for Node.js version, FFmpeg availability, Docker status, and other requirements. If `doctor` reports issues, address them before rendering.

## Still Stuck?

If none of the above resolves your issue:

1. Run `npx hyperframes info` to gather system and project details
2. Check [GitHub Issues](https://github.com/heygen-com/hyperframes/issues) for similar reports
3. Open a new issue with the output of `npx hyperframes info` and steps to reproduce

## Next Steps

<CardGroup cols={2}>
  <Card title="Common Mistakes" icon="triangle-exclamation" href="/guides/common-mistakes">
    Coding pitfalls that break compositions
  </Card>
  <Card title="Rendering" icon="film" href="/guides/rendering">
    Rendering modes, options, and tips
  </Card>
  <Card title="CLI Reference" icon="terminal" href="/packages/cli">
    Full list of CLI commands
  </Card>
  <Card title="Contributing" icon="code-branch" href="/contributing">
    Report bugs and contribute fixes
  </Card>
</CardGroup>
