#Frequently Asked Questions

#How to Load QuickUI in UE5 Development Environment?

In the UE5 development environment, use LoadURL to load http://localhost:3000 to load QuickUI in development mode.

After the development tools are activated, use the shortcut Ctrl + Shift + I to open the browser console and view QuickUI console output information.

#Connection & Communication

#isConnected is always false

Problem: isConnected from useUEContext() always shows "Disconnected".

Cause: The web page is not running inside UE5's web browser widget, so the UE5 engine hasn't injected the ue communication object.

Solution:

• Make sure the HTML file is loaded through UE5's QuickUI plugin web browser widget, not opened directly in a desktop browser
• Run the game (Play) in the UE5 editor; the Web UI will connect automatically
• During development, check window.ue in the browser console to verify the UE communication object exists

#Event sending fails: ue.uecommand.emitjsonevent is not a function

Problem: After calling the send function returned by useQuickUIEventSender, the UE5 side doesn't receive the event, and the console reports emitjsonevent is not a function.

Cause: The QuickUI plugin version in UE5 is too old, or the uecommand object is incomplete.

Solution:

• Ensure the latest version of the QuickUI plugin is installed and enabled in the UE5 project
• Verify that the event name in the UE5 blueprint matches the name passed to useQuickUIEventSender('eventName')
• During development, enter window.ue in the QuickUI DevTools console to check if the UE communication object exists

#useQuickUIEventListener callback never fires

Problem: Events are listened for with useQuickUIEventListener, but the callback never executes.

Cause: ue-connect requires a root-level component to call useQuickUIEventListener first to establish the event listening channel.

Solution:

// A top-level component must call useQuickUIEventListener first
function App() {
  // Call once in the root component, event name can be anything
  useQuickUIEventListener('UEcallback', (event) => {})

  return (
    <UEProvider>
      <YourComponent />
    </UEProvider>
  )
}

Recommended approach: Use UEProvider directly, which internally initializes event listening.

#Mouse & Input

#Web UI click events pass through to the UE5 scene

Problem: When clicking buttons or elements on the Web UI, mouse events pass through to the UE5 game scene, causing the UE5 character or camera to respond.

Cause: The data-nohit attribute was not added to the Web UI elements.

Solution: Add the data-nohit attribute to containers or elements that should block mouse event passthrough:

<div data-nohit className="ui-panel">
  {/* Mouse events in this area will not pass through to UE5 */}
  <button onClick={handleClick}>Click Me</button>
</div>

useUEMouse automatically detects elements with data-nohit and disables mouse event forwarding to UE5 when the cursor is over those areas.

#Right-click context menu appears in Web UI

Problem: The browser's default right-click context menu pops up when right-clicking on the Web UI.

Solution: Use useInputBlocker to disable the context menu:

import { useInputBlocker } from 'ue-connect'

function App() {
  useInputBlocker({ disableContextMenu: true, disableTabKey: true })
  // ...
}

#Tab key causes focus jumping

Problem: Pressing the Tab key causes browser focus to jump between elements, interfering with UE5 operations.

Solution: Disable the Tab key in useInputBlocker as well:

useInputBlocker({ disableContextMenu: true, disableTabKey: true })

#Build & Deployment

#Images not displaying in UE5

Check if the packaging configuration Load the Built HTML is missing

#Style issues or scripts not executing after build

Problem: After running rspack build, the HTML file shows broken styles or script errors when loaded in UE5.

Cause: The Rspack build output references external JS and CSS files, which UE5 cannot load.

Solution: After building, use the merge-html tool to inline all resources into a single HTML file:

npm run build
npm run merge-html

#@ alias causes TypeScript errors

Problem: import App from '@/pages/template/App' throws a module not found error.

Cause: The TypeScript configuration doesn't recognize the @ path alias.

Solution: Check that tsconfig.json has the paths configured correctly:

{
  "compilerOptions": {
    "paths": {
      "@/*": ["./src/*"]
    }
  }
}

#UE5 Integration

#autofit.js scaling is not working

Problem: The Web UI size is incorrect in UE5 and doesn't scale according to the design resolution.

Cause: The autofit.js initialization requires the Fit={true} prop to activate.

Solution:

// Pass the Fit prop to the App component
<App Fit={true} />

// Or initialize directly in the root component
useEffect(() => {
  autofit.init({
    dw: 1920,     // Design width
    dh: 1080,     // Design height
    el: 'body',
    resize: true,
    transition: 0.25,
    limit: 0.3    // Scale limit
  })
}, [])

#UE5 side not receiving QuickUI custom events

Problem: The frontend sends events via useQuickUIEventSender, but the UE5 blueprint/UMG doesn't receive them.

Cause: Event name mismatch between the frontend and UE5 backend.

Solution:

• Frontend event names correspond to the UE5 backend's QuickUIListenEvent node
• Event names for listening correspond to the UE5 backend's QuickUIEventCallBack node
• Keep event names identical on both sides (case-sensitive)

// Frontend sending
const sendEvent = useQuickUIEventSender('playerUpdate')
sendEvent({ health: 100, ammo: 30 })

// UE5 side uses "playerUpdate" as the event name for QuickUIListenEvent

// Frontend listening
useQuickUIEventListener('gameStateChange', (event) => {
  console.log('Event received:', event)
})

// UE5 side uses "gameStateChange" as the event name for QuickUIEventCallBack