See
and
There are two different “sonoff zigbee 3.0 usb dongle plus” models; ZBDongle-P & ZBDongle-E, which? Note that if you have ZBDongle-E model (a.k.a. Dongle-E) then that is the wrong firmware for it. Read:
and
Are you using ZHA (Zigbee Home Automation) integration or Zigbee2MQTT (a.k.a. Z2M)?
Regardless, you need to manually stop or disable the Zigbee gateway solution before doing anything.
ZHA integration supports automatic backup + restore for both ZBDongle-P & ZBDongle-E so no issue.
Zigbee2MQTT only support automatic backup + restore for ZBDongle-P so if it is a ZBDongle-E then recommend do a manual backups with zigpy-cli and be prepared to restore it if upgrade wipe config:
https://github.com/zigpy/zigpy-cli
That is assuming that using Zigbee2MQTT and not the ZHA (Zigbee Home Automation) integration, and this forum was at least initially only about the native ZHA integration which third party integrations like Zigbee2MQTT use the forum for third party integrations (because as far as Home Assistant known Zigbee2MQTT communicate using MQTT) → https://community.home-assistant.io/c/third-party/15
It is also assumed that he has the ZBDongle-P model and not the ZBDongle-E model. Zigbee2MQTT does not currently support automatic backup for Silicon Labs based adapters → https://github.com/Koenkk/zigbee-herdsman/issues/319
No offence meant. I use both ZHA and Zigbee2MQTT myself, though I would not just assume that everyone posting in this subforum uses ZHA and Zigbee2MQTT as many do not consider this.