@gauravkaushik Did you make the new field required?

Yes

well, surely, if it’s required, you already have the values you intend to enter for all the existing records — in that case you could start adding the field as non-required, in which GC should not ask for a migration value, then add all unique values in, then make the field required once you have all the data in and before you enter any new record.

Thanks! I think your solution will work in this case. But hypothetically speaking, in highly concurrent systems where multiple objects of that type are getting generated in a matter of seconds, I might miss the newly generated ones while the migration is underway. I think it'll be a better alternative if we had a way to somehow reference existing fields when specifying migrationValues for the new field.