What is the output of fastboot --version ? [1]
I found the error message crop up twice on the forum.
- Fastboot: error: cannot generate image for userdata (SOLVED)
- Add a warning to /e/ install instructions to avoid fastboot -w failing?
I do use a SIM card when I install, but I am not aware of it being critical Edit, use of the SIM card to make connections on manufacturer OS is actually recommended on the LineageOS install page.
[1] Currently 34.0.5 (October 2023)