SYMPTOM:
"Index out of Range" error message is returned in Strategy Web 9.x when trying to edit a subscription that uses an attribute that previously had a compound key, to one that no longer uses a compound key.
CAUSE:
Changing the schema in this manner will affect all objects that depend on this attribute such as subscriptions, filters and prompts. In the case for subscriptions, both values for the compound key are stored in the definition of its personalization (prompt answer). When trying to edit the subscription, the "Index out of Range" error is displayed because one of the values in the prompt answer does not point to any attribute form.
This is the reason for the warning when trying to modify the attribute ID:
ACTION:
Since by changing the ID form of the attribute (compound to single key), the attribute has become a new attribute, personalizations based on that attribute may no longer continue to work and should be recreated.
