If you change any of your application’s tables in the process of updating your application, data from the previous version of your application will likely be incompatible. This requires that you convert data at the customer site to the new table definition for the updated version of your application. Changes that make existing data incompatible include:
In addition, if your table uses Microsoft Dynamics GP fields and the storage size of one of the fields changes, you’ll need to convert the data for that table. Refer to Updating an Application for more information about writing a table conversion procedure.