We added "Found in Build" as a required field for a Defect. However, if later one tries to convert a Backlog Item to a Defect, the conversion will fail. Since "Found in Build" isn't a field in a Backlog Item, V1 bails. Alternatives would be to simply put a placeholder in the "Found in Build" field (e.g., <Found In Build Entry Required>) or ask the user to enter the field value during the conversion.

Whichever approach is taken would be fine with us. However, as this problem would naturally arise for any other required field for a work item type when a conversion to that type from a work item type without that field, a consistent approach to resolving this issue for all such fields would be desired.

We have a workaround of unchecking the Required checkbox for the field, doing the conversion(s) and setting a value for the field, then rechecking the checkbox. A bit clunky, but it will do for now.

This issue was also raised about a year ago by the Idea "Allow conversion of story to defect and vice versa even if required field exists on source asset". I finally set up a search string that would find similar topics w.o. ten pages of almost related issues showing up as well.