The Original Prusa XL is equipped with an ESP Wi-Fi module. This module is part of the xBuddy board. In case the printer cannot find the ESP module, this error will appear.
Error name: ESP not connected
Error code: #17533
Make sure that you have a USB drive with the latest firmware connected to the printer. Go to the printer menu in Settings -> System -> Factory reset -> Hard Reset (USB with FW needed).
After that, you will need to go through the initial printer calibration again.
In case that does not solve the issue, contact our Customer support.