Start and due dates are incorrectly set on epic creation

An internal user reported:

I found a time zone issue with Epics on GitLab.com. When I set the start date and the due date to N and M for a Epic, the Epic will have N - 1 and M - 1 for each after it is created. I did this operation when it was 01:30 in UTC+0 and the time zone setting on my account was [UTC+9 Osaka]. It was also reproducible when I set to [UTC+0].

Screen_Recording_2021-07-26_at_11.38.55_AM

Why is this happening?

The date picker used in epic_form.vue emits a datetime value converted to UTC+0.

In the demo, the picked date is July 1 (UTC+9) but the actual value stored is 2021-06-30T15:00:00.000Z and this gets included in the epic create GraphQL mutation. Note that both startDate and endDate are stored as dates without timezone information in the backend.

Solution

Parse the emitted date values from the date pickers and format them like done in sidebar_date_widget.vue.