[OutSystems UI] Error message when showing Tabs in Reactive
Forge component by OutSystems R&D
Application Type

Hi, I'm developing an application with Outsystems Reactive and I'm using the Tabs component from OutsystemsUI.

My problem is that when I open the page, an error message is being shown: Cannot read property 'classList' of undefined.

Tabs are inside a webblock, 

Does anyone know a solution for this? I have tried to put the Tabs directly in the screen but the error keeps showing.

In addition, Chrome console shows this message:

Logger.js:476 [2021-07-06T07:58:02.228Z]: Cannot read property 'classList' of undefined 

TypeError: Cannot read property 'classList' of undefined

    at init (/scripts/OutSystemsUI.Navigation.Tabs.mvc.js?DbTZo6GeEsz9orh0nluF7Q:2299:23)

    at /scripts/OutSystemsUI.Navigation.Tabs.mvc.js?DbTZo6GeEsz9orh0nluF7Q:2444:5

    at Controller.e.safeExecuteJSNode (/scripts/OutSystems.js?OPjyhkVD_VNUyv8gjuX9hw:14:28262)

    at Controller._onReady$Action (/scripts/OutSystemsUI.Navigation.Tabs.mvc.js?DbTZo6GeEsz9orh0nluF7Q:1611:33)


Hey! you're missing the content of the tabs! A tabbed content for each tab header.

Let me know if it helped you.

Best regards,


It worked! Thank you very much.

Hi Diego García-Denche,

Cannot read property 'classList' of undefined error occurs because the Navigation\TabsContentItem is missing



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