Continuous Loading

When the VR Client becomes stuck in a continuous loading state and fails to establish a session, several underlying causes may be responsible. The following causes should be investigated in order.

## Cause 1: SteamVR Is Not Installed

SteamVR has not been installed on the rendering server, preventing the VR session from initializing.

### Solution

Install SteamVR on the rendering server. Refer to the [SteamVR installation guide](https://www.pingxingyun.com/online/vr3_2.html?id=449) for step-by-step instructions.

## Cause 2: SteamVR Does Not Start Properly on the Server

SteamVR is installed but fails to start correctly due to missing or outdated system dependencies.

### Solution

1. Verify that the **sound card driver** is installed correctly on the server.
2. Ensure the **graphics card driver** is updated to the latest available version.
3. Confirm that all required **VC++ redistributable libraries** are installed.
4. Refer to the [SteamVR environment setup guide](https://www.pingxingyun.com/online/vr3_2.html?id=449) for a full list of prerequisites.

## Cause 3: Firewall Is Not Disabled

The system firewall is blocking the communication required to establish the VR session.

### Solution

Disable the firewall on the rendering server, or configure firewall rules to allow LarkXR traffic through the required ports.

## Cause 4: UDP Port Is Unavailable

The UDP port required for VR streaming is not open or is being blocked.

### Solution

Open the required UDP port on the rendering server. Ensure that the port is not blocked by the operating system firewall, network firewall, or router.

## Cause 5: Security Software Blocking Application Startup

Third-party security or antivirus software is preventing LarkXR or SteamVR from launching.

### Solution

Temporarily disable any active security software or antivirus programs on the rendering server, then retry launching the VR session. If the issue resolves, add LarkXR and SteamVR to the security software's exception list.

## Cause 6: SteamVR Version Incompatibility

The installed version of SteamVR is outdated or incompatible with the current LarkXR build.

### Solution

Update SteamVR to the latest version via the Steam client, then restart the rendering service and retry the session.

## Cause 7: Communication Problem Due to Special Network Configuration

In certain network environments, the default IP address `0.0.0.0` used for UDP packet transmission is not compatible. The VR rendering server must be configured with an explicit IPv4 address for communication.

### Solution

1. On the rendering server, open the configuration file located at `larkxr-render/application.properties`.
2. Set the listening IP address to the server's actual IPv4 address by configuring the relevant property as shown below.

![](https://docs.paraverse.cc/media/202504/8d97c3c2bee04591ac39c0019f3517591137.png)

3. Save the file and restart the rendering service.

## Notes

- Work through the causes in order, as the most common issues (SteamVR not installed, driver problems, firewall) account for the majority of continuous loading cases.
- Always ensure SteamVR is fully operational on the server before troubleshooting network-related causes.