@GeorgiaT16784649 Hello, I believe that in order to do that you would need to delete all existing instances of that particular class using pxDeleteClassInstances then the option to add new keys should unlock. However, I do not advise changing your class keys if your application is already in production.

Hi @GeorgiaT16784649,

 You may need to delete the all records or Instances for that class. Example if you want to add class key to data class we need to delete the all records from the data type then only we can add or remove class key.

Regards

Mohd Qizer Uddin 

@GeorgiaT16784649 Yes, but it is a two part change. First update the database: add the new column to the table, make it part of the composite primary key, and backfill values for existing rows so the new key is non null and the whole key stays unique. Next update Pega: create a property for the new column if it does not exist, map it to the column on the class, then open the Class rule and add this property to the Keys list in the same order your DB uses. If you use a Savable Data Page, update its save plan so the new key is set before save. Review activities, data transforms, and Obj methods that open or save by keys and pass the new key too. Update Report Definitions and joins that rely on the key columns. Expose the field on screens or integrations so new records actually populate it. After deploying, clear caches, test create and open by keys, and verify no duplicates or nulls break the primary key.