Cannot read property  of null (reading 'addEventListener')

Hello guys, is someone willing to help me find out this error? 

This error occurs on the login screen where I am implementing a 2fa verification.

thank you in advance.


Hi Alex,

You are using a ButtonLoading widget on the True branch of the If on the content inside the form (for ImputControl=1), with a binding to the boolean variable IsExecuting, and with no button inside it. 

Either move the Login button inside this widget, or simply remove the widget from the page.

Hope this helps.

Best regards,

Paulo Moreira

Hi Paulo,

I have the same issue but different error like Cannot read property  of null (reading 'removeEventListener').
I have created a master detail screen, it is working as expected in full page view, but when i resize screen to mobile view then clicking on a listitem there also it will be working as fine but when i back to full screen right after listitem click in mobile view, then i am getting this error when i click on listitem in full page view.

Can you suggest me where is the issue.


Thank you so much, problem solved!

I just wondering how you did it?

Hi Alex,

These widgets have some javascript attached to it, to improve its functionality. If something fails or is missing, then the client side exception is thrown.

I've had some headaches similar to this one in the past, so....

Glad I could help.

Best regards,

Paulo Moreira

Again,  thank you so much!

For beginners this can be a big barrier. 

I  appreciate your time spent helping me!

You’re welcome. Glad I could help.

Best regards,

Paulo Moreira

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