Hey Manjeet Singh Seegriwal,
I ran into the same error – "Missing duration or end time for task: null" – when using Google Gantt. The issue was with the data going into the chart. Google Gantt needs each task to have either:
Start date + End date or
Start date + Duration
If both end date and duration are empty, it throws this error.
In the “Row entity” of the widget, make sure you’re using the entity where your tasks are stored. Also check that for every record you pass to the chart, you’ve got either an end date or a duration filled in.
I fixed it by updating my data so no row had a missing end date/duration, and the chart worked fine after that.
Regards
Reemali