This question relates very much to Unable to Set Created date even after enabling Set Audit Fields
However, my problem is specifically related to the Knowledge__kav SObject.
I'm trying to import existing knowledge articles into salesforce from a legacy system and for compliance reasons, I need to keep the same CreatedDate.
I've given the running user a permission set, which has the permission "Set Audit Fields upon Record Creation" enabled. When trying to set CreatedDate on Account and ContentVersion sobjects, it works fine, but not for Knowledge__kav.
I tried importing the data both via the API and via APEX. Via the API, the insert is successful, but the CreatedDate is overwritten with the current DateTime. A before insert trigger revealed that CreatedDate was null before insert. Via Apex, I get the error "FATAL_ERROR System.SObjectException: Field is not writeable: Knowledge__kav.CreatedDate"
I can't find any documentation stating that the behaviour of "Set Audit Fields upon Record Creation" is different for Knowledge__kav. Does anyone know?