Print Errors

The Print Errors API lets you intercept all error output coming out of the Unity Module — runtime errors, JavaScript errors thrown from jslib files, and Debug.LogError calls from your C# code — before they reach the browser console.

Type Definition

Type Definition

function printErr(message: string): void;

Implementation

By default, Unity routes its error output through console.error. When a printErr handler is provided to the Unity Config, Unity will call your handler instead of writing to the console directly. This is the counterpart to Print and is the recommended channel for forwarding Unity errors into custom logging, error reporting (e.g. Sentry), or an in-app diagnostics panel.

Both runtime problems thrown by the engine and jslib/JavaScript errors flow through this handler.

info

The handler is captured once during initialisation and passed to createUnityInstance. Changing the function reference after the Unity Instance has booted will not have any effect, so prefer a stable reference (for example via useCallback or a module-scope function).

caution

The handler replaces the default console output. If you still want messages in the browser console, call console.error from inside your handler.

Example Usage

A basic implementation could look something like this. In the following example we'll forward every Unity error to both the console and an error reporting service.

App.jsx

import React from "react";
import { Unity, useUnityContext } from "react-unity-webgl";

function App() {
  function handlePrintErr(message) {
    console.error("[Unity]", message);
    errorReporter.captureMessage(message, { level: "error" });
  }

  const { unityProvider } = useUnityContext({
    loaderUrl: "build/myunityapp.loader.js",
    dataUrl: "build/myunityapp.data",
    frameworkUrl: "build/myunityapp.framework.js",
    codeUrl: "build/myunityapp.wasm",
    printErr: handlePrintErr,
  });

  return <Unity unityProvider={unityProvider} />;
}