Can I automate the update of custom date fields on linked cards when the trigger card field changes?

[Shauna Strickland]

I have a custom date field on my primary card and I would like for the same custom date field on any cards linked to that primary card to be updated when the date field of the primary card is changed. I have tried several automation rules, but I get either a 'Couldn't read date in "{2025-12-31T17:00:00.000Z}".' error or 'A possible loop was detected' error. The one time the rule worked, the custom date field on the linked cards was changed to the current date (like if I had selected the Now date variable) rather than changing to the custom field variable of the trigger card (which was 12/31/25) and I received the loop error message.

The rule I used when the custom date fields on the linked cards changed to the wrong date and I received the loop error message was: When custom field "Project End Date" is set, for each card linked in the attachments, set custom field "Project End Date" to "{trigger{{%Project End Date}}}"

The rule I used when the correct custom date couldn't be read was: When custom field "Project End Date" is set, for each card linked in the attachments, set custom field "Project End Date" to "{{customfieldvalue}}"

I know that there are built in automations for Start/Due Dates or for when custom date fields are in/not in specific time frames, but I'm stumped regarding how to write an automation rule for my specific scenario. Any guidance is appreciated. Thank you.

[Lipakshi Narang]

Hi,

I have tried working on the automations that you have shared.
However, I dont find the action "set custom field" supporting a custom field with date type.

Can you please help me understand the type of the custom field you have set in the linked cards?

Thanks & regards,
Lipakshi

[Shauna Strickland]

It's a date field. And I can select it from the drop down list of custom fields that are available in the "set" custom field automation trigger.

[Lipakshi Narang]

Hi

Thank you for the updates.

I have tried working on the rule but currently, there isn't any predefined action that fulfills the second part of the requirement.
The set date custom field has only some options available which doesn't seem suitable here.

Please feel free to reach out to us if there are ant other queries!

Thanks & regards,
Lipakshi Narang

[Shauna Strickland]

Thank you, but I already knew there wasn't a predefined action that let me complete the scenario. Are you also saying that there isn't any way in which to carry out the second half of the automation?

[Lipakshi Narang]

I am referring to the last part of the scenario here: set custom field "Project End Date" to "{trigger{{%Project End Date}}}"

We have two options to set the custom field's value. The first one doesn't support field type date and the second one has some limited options which doesn't offer setting the custom field using variables. 

[Shauna Strickland]

Thank you; that verifies that I cannot automate the desired action.