I think this is more a problem with the Updater, the 2.4.1 appeared in my updater ok, and that was the expected behaviour. However there have been a run of this report with Fairphone.
There is this solution Issues with the Updater and a solution. It has also been reported to fail, however please try with the addition of full shutdown Power + Volume UP and reboot your device after the proceedure.
- Please note shutdown difficulties with Fairphone https://www.reddit.com/r/fairphone/comments/17s3hd6/why_will_my_fp_not_shut_down/, wrong link, I meant Cannot shut down or restart after latest Fairphone update - Fairphone 4 - Fairphone Community Forum and read a little beyond the marked solution (or search the forum).
If you need to try again, please also close all Advanced Privacy sliders and Shutdown / reboot.
If still fails; does you Updater allow “local update” in 3 dot top right menu of Updater?