Gold Client has been periodically enhanced over the years to manage this situation so the user does not need to take any specific actions; however, there may still be isolated instances where a table structure delta exists between a source and target system that causes an issue during the data import process. Those incidents will need to be analyzed on a case-by-case basis to determine what actions are required in order to resolve. Freely submit a support case and the Qlik team will respond accordingly.
The most common occurrence for a delta is when customers append a custom (Z) field to an SAP table; this development change has been deployed in DEV and perhaps other lower-level systems but has yet to be promoted to higher-level systems or even to Prod.
Structural deltas may also occur when the source and target systems are on different SAP versions or support packs and because of the potentially significant number of deltas that may be introduced by SAP in the upgraded versions, it is Qlik's best practice recommendation that the source and target systems always be on the same SAP version and support pack in order to avoid unforeseen issues.