WEBJS Engine: getChatModel error when fetching groups/chats

[malikyousef]

Hi,

I'm using WAHA Plus (version 2026.1.4) with the WEBJS engine on Railway.

The session connects successfully and sending messages/images works fine.
However, when I try to fetch groups or chats, I get this error:

TypeError: Cannot read properties of undefined (reading 'update')
window.WWebJS.getChatModel

Stack trace:

• at window.WWebJS.getChatModel (evaluate at WPage.evaluate)
• at window.WWebJS.getChats
• at async WebjsClientPlus.getChats
• at async WhatsappSessionWebJSPlus.getGroups

Endpoints affected:

• GET /api/{session}/groups → 500 error
• getChats / getContacts also fail

What works:

• Session status: WORKING
• POST /api/sendImage → 201 success
• POST /api/startTyping → 201 success
• POST /api/sendText → works

Environment:

• WAHA Plus 2026.1.4
• Engine: WEBJS
• Platform: linux/x64, Railway hosting
• Browser: /usr/bin/chromium

Is this a known issue with the WEBJS engine? Is there a fix or workaround?

Thank you