Getting UI Exception "Cannot read properties of null (reading 'querySelector') "


I am using Star rating widget, Navigation wizard and side menu on the same screen of the mobile app in order to meet up the business requirement. But while using this I am getting "Cannot read properties of null (reading 'querySelector') " and null is not an object(evaluating 'activeScreen.querySelector'). I suspect this is because of star rating widget only, as far I have analyzed. For time being I am handling this error on exception handler in order to avoid this error appearing on front end and still it is getting logged on the preview console continuously and some of the users were started getting "null is not an object(evaluating 'activeScreen.querySelector')" error on mobile app also. It would be much helpful, if get some help to fix these errors. PFA.

Error message get logged in console:

[2022-03-04T05:51:36.569Z]: Cannot read properties of null (reading 'querySelector') 

TypeError: Cannot read properties of null (reading 'querySelector')


    at Controller.safeExecuteJSNode (

    at Controller._toggleFieldsetDisabled$Action (

    at Controller._onParametersChanged$Action (


    at d (

    at f (

    at Object.p [as tryCatchFinally] (

    at Controller.safeExecuteClientAction (

    at Controller.onParametersChanged$Action (


Vignesh Balasubramanian

UI issue.png

Hi Vignesh,

Do you get this error as a result of an action (e.g. clicking a button), or does it pop up on screen render?

Hi @Ozan Can Çalı 

It is getting pop up on screen render and while clicking the navigation wizard widget as well.


I see. I suggest you create a new, empty module and start adding the widgets you use one by one. You can start only with the star rating widget and publish, and see if it gives the same error. Then you continue with adding the navigation wizard and the side menu.

If it gives the error again, even though you did not add any custom css or javascript, then it might be related to a bug on interrelation of those widgets on OutSystems side. 

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