How can I get already existing/created ticket to recognize a field change to REQUIRED?

[Steve Hooczko]

How can I get an already existing ticket, which was created before I set the field/field configuration to REQUIRED for a field, to recognize the field as required? If I'm creating a new ticket, the field comes up as Required and I must populate it. This does not apply to tickets created prior to the field change to REQUIRED.

[Nic Brough -Adaptavist-]

It can't - the flag is for Jira to enforce something during an action, not retrospectively demand issues be filled.

Existing issues that have no value for the field will demand it when they are edited, or transitioned (if the field isn't on the transition screen, people will have to go back to the issue view and edit the field, then retry the transition)

If you want to do some backfilling rather than wait for people to edit, it's probably easiest to run a search for "project = x and <field> is empty", then use bulk-edit from the options menu to set values on the issues.