For a long time, we have shown an error to the user if they attempt to create a column of type Ref, where the referenced table uses _RowNumber as the key. This is because _RowNumber is an unstable key that can lead to data loss.
We are making a couple changes to this:
- We will expand the cases where the error is shown to include columns of both type Ref and of type List of Ref
- We will not show the error in either case if the column is a virtual column or the referenced table is read-only*
If your app has a table that meets these conditions, you will need to change the key of that table to not use _RowNumber. If you need assistance doing this, we have a full guide on keys here: https://help.appsheet.com/en/articles/1023086-what-is-a-key
*If you were shown the error in the past few days, but with a virtual column or a read-only table, it was my mistake and the error has gone away by now. See Column Error when Referencing (REF) data from other table in the spreadsheet