Thanks to @Diane POMABIA  I solved my issue. The problem was just my STLink version not up-to-date, you must have at least V2J38 STLink FW Version to process regression! Now with V2J42S7 everything is fine!

@Diane POMABIA , @Jocelyn RICARD  hello, I'm working on a STM32U595 and I encountered the same issue (not being able to do the regression from RDP2 to RDP1 even with my OEMKEY1 and 2 set etc.First of all I configured OEMKEY1 and 2 : Then I followed t...