TrueNAS Fangtooth RC fails to install

I thought I would try Fangtooth as it sounded like the RC was pretty stable but I can’t even get past the installer. Here’s the error:

Update
Error: [EFAULT] Traceback (most recent call last): File "/usr/local/lib/python3.9/runpy.py", line 197, in _run_module_as_main return _run_code(code, main_globals, None, File "/usr/local/lib/python3.9/runpy.py", line 87, in _run_code exec(code, run_globals) File "/var/db/system/update/squashfs-root/truenas_install/__main__.py", line 21, in < module > from .utils import getmntinfo, get_pids File "/var/db/system/update/squashfs-root/truenas_install/utils.py", line 9, in @dataclass(frozen=True, kw_only=True) TypeError: dataclass() got an unexpected keyword argument 'kw_only'

How are you installing TrueNAS?

Through the “System / Update” page: TrueNAS-13.0-U6.7 → TrueNAS-25.04-RC.1|

Did you follow the migration guide?

https://www.truenas.com/docs/scale/25.04/gettingstarted/migrate/

Oh, I see " Attempting to migrate directly to 24.10 or later releases using the UI is not supported." - strange that it would appear as an option in the UI.

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Can you upgrade to an earlier release in the list? then you can upgrade again

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I have upgraded by booting from a USB stick. Thanks all