macOS-upgradeassistant

Hello all! I was hoping someone could please help me! Have a mid 2012 MacBook Pro.. Using OCLP to get a new macOS installed. The USB-installation works perfectly. The OS installs, but, the next step, the macOS-upgradeassistant fails. I’ve tried Sonoma, Ventura, Catalina.. they all fail! Included a picture (please forgive me, it’s in Swedish). The error states something like this.. “an error occurred while the program-update was being prepared” .. Anybody ran into this before.. ? I’m connected with a wired connection.. connected to Wi-Fi before install as well.. Any ideas are greatly appreciated!