I just updated a project from an older version of daypilot-pro-react (2025.3.6519) to the latest one (2026.1.6860) and I discovered that in version 2025.3.6631 a breaking change (at least for me) was introduced without any mention on it in the release notes.
When the scheduler configuration has the property “scale“ set to “Manual” and the timeline property is either missing from the config or set to [] the <DayPilotScheduler/> component will throw an error complaining that it doesn’t find a start property (I assume it is looking for it in the empty/undefined timeline). This behavior is different in previous versions where the component rendered but had an empty timeline.
Why this matters and why it affects me? That is because I need to create a manual timeline based on some data from the backend and that takes a second to fetch so I start with and empty array and when I have the necessary start and end dates then I recreate the timeline but because now the component throws an error with an empty timeline it crashes the whole app.
The simplest way to reproduce this is to clone the project from https://code.daypilot.org/50496/next-js-scheduler and in the app/scheduler/Scheduler.tsx just replace the scale at line 13 from ”Day” to “Manual” and run the project. with the version that it comes with (2026.1.6804) it will crash but with 2025.3.6614 it will run but show an empty timeline.