gantt: marker {i} has no drawable date or fr...

Warnings reference › gantt.marker.*

Identifier

gantt.marker.*

Raised by

Gantt

Since

1.88.4

What happened

A markers entry for a Gantt timeline could not be drawn: it was not an object, or its date (or its from/to range) was missing or not a day-number, an ISO date string or a Date. The marker is skipped and the rest of the plan draws normally.

The fix

Give each marker a date, or a from/to pair, as a day-number, an ISO YYYY-MM-DD string or a Date.

The smallest fix

gantt.mount(el, { markers: [{ date: '2026-06-01', label: 'Go-live' }] });

Reference

Covered in full at the API reference.