- Set up two Jira instances, populate them both with issues, and applink them.
- Set up a remote issue picker field on one instance (this is all we need the applink for).
- Check that field's config scheme, and that scheme's oneAndOnlyConfig, and see if they have the same ID. If they do, then create a new field config and assign it to the scheme in place of the old one (you'll most likely need to do this programmatically through the script console).
- Make sure the field is mapped to an issue creation screen, then attempt to create an issue via that screen.
Expected: The issue is successfully created.
Actual: The creation fails with an error, whose root cause is given as:
This happens because the field in the screen has a hidden fieldConfigId parameter - which does indeed contain the ID of the relevant field config - but this gets treated on the back end as though it were the ID of a field config scheme. Very often these are the same for any given custom field, but they do not have to be.