Here is how to to upgrade firmware on a Ubiquiti EdgeRouter X. Remember this will erase all 3party software and setting line OpenVPN or WireGuard.
Download latest firmware for your device at https://www.ui.com/download/software/er-x
(latest version 2023-07-23 are Firmware v2.0.9.hotfix.6)
1. Backup your device
2. Log into to console
3. Click on system
4. Click on upload
Wait until upload is finished, and confirm reboot.