The instance has been updated by another user or property handle and can not be refreshed or written. If the instance shall be overwritten, try to save the instance with the overwrite option (system interface).
When checking instance selections, updated instances are usually reread in order to display the proper instance state. When the instance to be reread is, however, updated by another user or property handle, changes are discarded without saving the instance. Changes in subordinated instances are maintained.
When an instance in a reference has been removed or replaces by another instance, all changes are discarded including subordinated instances.
The error typically happens in OSI scripts when using updating access paths, i.e. access paths with selector elements (person.children(0)...) or calling an updating function (see example).
// updates instances in two different copy handles for children
person.children(0).name = "Miller";
person.children(0).first_name = "Paul";
person.save(); // couses an error since both child instances changed
// solution: select an instance in the children's origin
if ( person.children.tryGet(0) ) {
person.children.name = "Miller";
person.children.first_name = "Paul";
}
person.save(); // couses an error since both child instances changed