How do I create a report that shows when a custom field was last updated?

[Anita Taylor]

I use Jira Next Gen.

I would like to create a report that shows the date when a specific custom field was last updated. Specifically, I want to pull a report that shows issue was created on Date and custom field was updated on date, so that I can subtract the two dates to get the number of days between when the issue was created and when the custom field was changed.

Looks like the out-of-the-box JQL operators (such as CHANGED) can not be used on custom fields, only specific out-of-the-box fields. 

I found this similar question from four years ago, but the answer is not helpful.

[John Funk · Accepted solution]

Hi Anita,

I usually create a custom date field for capturing the timestamp - something like CF Updated.

Then use Automation For Jira to set the value of the new custom field to Now() when the original field is changed.