gantt: projectEpoch {value} is not a date or a day number; the plan is rendered against the Unix epoch (day 0 = 1970-01-01).

Warnings reference › gantt.projectEpoch:*

Identifier

gantt.projectEpoch:*

Raised by

Gantt

Since

1.52.0

What happened

projectEpoch anchors the plan's day numbers to real dates. The value given could not be read as a Date, an ISO date string or a day number, so the anchor is 0 and every date on the axis is counted from 1 January 1970 - which is why a plan can render with dates decades out.

The fix

Pass a Date, an ISO YYYY-MM-DD string, or a day number.

The smallest fix

createGantt({ tasks, projectEpoch: '2026-01-05' });

Reference

Covered in full at the API reference.