Hi @Cosmin Stirbu ,
The engineering team confirmed you can only copy from production to staging slots, or from a staging slot to another non-prod slot but not from staging into prod slot (which is why you're getting that error). It’s to prevent you from accidentally copying over your production config and losing it.
The API you shared is there so you can copy content and config from one slot into a new slot, or after swapping into production, you can copy production content and config back into the staging environment.
Hope that helps. Please let us know if you have further questions.
-Grace