Steps to follow - Go to project - Click on the 3 littles dots on a card - Go to Burndown Chart - Add a custom filter on the date_group_by field -> this.fields[condition.field].selection[0] Cause of the issue The date_group_by field selection should be declared as a list, not a tuple opw-2819936 closes odoo/odoo#91397 X-original-commit: e3254a882199f229e4a8b4f38ce7f7529fd8da46 Signed-off-by: Hubert Van De Walle <huvw@odoo.com>