Code 900

The `code 900` error indicates a failure in the VR rendering service startup. This error can be triggered by several environmental or configuration issues on the deployment server. The following causes should be investigated in order.

## Cause 1: LarkXR Is Installed in a Directory with Chinese Characters

The LarkXR deployment path contains Chinese (non-ASCII) characters, which can cause the rendering service to fail during initialization.

### Solution

Reinstall LarkXR to the root directory of a drive letter (e.g., `C:\LarkXR`), ensuring the full installation path contains only English alphanumeric characters and standard symbols.

## Cause 2: Incorrect SteamVR Path Configuration

The SteamVR path entered in the LarkXR configuration is incorrect or uses an invalid format.

### Solution

1. Open the LarkXR configuration and locate the **SteamVR Path** field.
2. Verify that the path points to the correct SteamVR installation directory.
3. Ensure the path uses the correct format — the directory separator should be `\\` (double backslash), for example: `C:\\Program Files (x86)\\Steam\\steamapps\\common\\SteamVR`.
4. Save the configuration and restart the rendering service.

## Cause 3: Rendering Server Not Restarted After Display Plug/Unplug

The rendering server was not restarted after a physical display was connected or disconnected from the server. This can leave the rendering service in an inconsistent state.

### Solution

Restart the rendering service manager to allow it to re-detect the display configuration. Refer to the [Restart the rendering service manager](https://www.pingxingyun.com/contribute/detail?topicId=10106&categoryId=3) guide for step-by-step instructions.

## Notes

- Always use a short, English-only installation path for LarkXR to avoid encoding-related startup failures.
- After any hardware change (such as connecting or disconnecting a display), always restart the rendering service manager before launching a session.