How to restore to old option value of custom field?

Hisamitsu Koga_cv95ul

Let me assume there is a custom field (select list (single choice)). There are two contexts in the custom field.

One project uses one context in this custom field and another project uses in another context in this custom field. One project has some existing tickets with this custom field and change the context to another context

in the custom field. This means option value in current existing tickets will be changed to another value. Right?

I would like to revert to original option value in current existing tickets. How can I do this? Please let me know.

Nic Brough -Adaptavist-

If a value is not valid for a field, you can't have it in that field, it needs to be changed to a valid one.

The best you can do is create a copy of the value that is becoming invalid, make the change, and then make the new invalid value "archived" in the options so that it can't be chosen again.

If you've already made the change and flipped over the invalid options to something, then you'll need to add the duplicate option, get a list of the ones that have been updated, and bulk-edit them to take up the new (but archived) option.