Jira Automation – Error updating Target End date using Error parsing date string in field Target End

[Karmandroid Singularity]

Hi everyone,

I'm trying to set up an automation rule in Jira, but I'm running into a date parsing issue.

Here are the relevant fields I'm working with:

Field Name	Type	ID / Source
Target Start	Target Start	customfield_17971
Target End	Target End	customfield_17972
Estimates (d)	Number	issue.timetracking.remainingEstimateSeconds

Both Target Start and Target End are expected to be Date fields. However, they show as “Target Start” and “Target End” under the Type column, which makes me unsure if they’re actually treated as Date fields.

What I’m trying to do:

When the Estimate is updated and Target Start is not empty, I want to automatically set:

Target End = Target Start + Estimate (in workdays)

My smart value expressions:

Variable for workdays:

{{issue.timetracking.remainingEstimateSeconds.divide(28800).round}} 

Update JSON:

ALL OF FOLLOWING HAS THE ERROR:

{
  "fields": 
  {
    "customfield_17972": "{{issue.customfield_17971.plusBusinessDays(workdaysToAdd).jqlDate}}"
  }
}

{
  "fields": 
   {
    "customfield_17972": "{{issue.customfield_17971.jiraDate.plusBusinessDays(4)}}"
    }
}

{
  "fields": 
   {
    "customfield_17972": "{{issue.customfield_17971.plusBusinessDays(4)}}"
    }
}

---

The problem:

I get the following error when the rule runs:

Error parsing date string: (customfield_17972)

I’ve verified that customfield_17971 (Target Start) is not empty during testing. Any idea why the .plusBusinessDays() or .jqlDate part is failing here?

Appreciate any help or clarification on this — especially if there’s a better way to format or update Date fields using smart values in automation!

Thanks!

UPDATE:

Tired another syntax as follow

WORKS!
------------------------------------
{
"fields": {
"customfield_17972": "{{issue.customfield_17971}}"
}
}

{
"fields": {
"customfield_17972": "2025-10-10"
}
}
---------------------------------------

DOESN'T WORKS (same error: Error parsing date string: (customfield_17972))
---------------------------------------
{
"fields": {
"customfield_17972": "{{issue.customfield_17971.plusBusinessDays(workdaysToAdd).format(\"yyyy-MM-dd\")}}"
}
}



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