search envelope-o feed check
Home Unanswered Active Tags New Question
user comment-o

Scheduler: Cannot read properties of null (reading 'calendar')

Asked by Leo
23 days ago.

Hi Dan,

On the live demo on https://javascript.daypilot.org/demo/scheduler/index.html, using a touch device (Android, Chrome) and some wild scrolling, I receive the following errors.

  • Number one happens when you scroll with momentum and then tap on the screen to stop scrolling. I don’t believe it has a real-world impact.

  • Error two happened directly afterwards - we see this pop up on Sentry quite a lot as well, however I can’t confidently reproduce it.

I have added the code sections - these are from the minified code but might help nonetheless.

bug javascript
Answer posted by Dan Letecky [DayPilot]
23 days ago.

Hi Leo,

The error #2 should be fixed now. There was an issue with events located next to a disabled parent row (treePreventParentUsage: true) when you tried to move them into the disabled row and started dragging very close to the event border.

The error #1 should never happen as the event handler is marked as non-passive. However, another safeguard was added which should prevent it.

If any of these errors still happen with the latest sandbox build (2025.3.6532), please let me know.

Comment posted by Leo
23 days ago.

Hi Dan,

Many thanks for all your fixes!

I can still reproduce #1 on the sandbox build by scrolling on a touch device with momentum, and then tapping & holding onto the grid (triggering an event creation).

- Leo

Comment posted by Dan Letecky [DayPilot]
23 days ago.

Thanks for the reproduction steps. Could you please give it a try with build 2025.3.6535?

Comment posted by Leo
23 days ago.

Perfect - it’s fixed and I can no longer reproduce it :)

Comment posted by Dan Letecky [DayPilot]
23 days ago.

Great, thanks for the update!

New Reply
This reply is
Attachments:
or drop files here
Your name (optional):
Tools
E-mail notifications
Feed
Related Questions
Infinite scroll
Drag&Drop with scrolling not working on tablet in scheduler
Angular Scheduler: Slow Scrolling on Resource Headers with Firefox
How to prevent the changed between dates when we implemented Rowfilter and Scrolling.
Schedule control and vertical scrolling
Scheduler: rowheader_scroll not scrolling on touch
Data for the view date range.
Scheduler: Infinite Scrolling issues on iOS
Calendar scroll speed
Datepicker in corner : events vanish
Show many days and allow scrolling horizontally
Issue With Horizontal Scrolling Reset in RTL Resource View
Can I preload the Scheduler to remove the delay in events appearing when scrolling?
Non-passive event listener

Products

Learn

Get Support

DayPilot Pro

Event calendar/scheduling AJAX components. Available for JavaScript/HTML5/jQuery, ASP.NET, ASP.NET MVC. Build resource booking, project management, time tracking applications, personal and shared event calendars.