Is there a way to root a Samsung Galaxy S4 running LineageOS 17.1?

Question

Following the "Samsung (System-as-root)"* instructions, I cannot get Magisk to patch lineage-17.1-20210304-nightly-jfltexx-signed.zip for a Samsung Galaxy S4 (SGH-M919). Magisk throws an "unsupported/unknown image format" error.

^{*since Magik says SAR=yes}

Is there a way to root a Samsung Galaxy S4 running LineageOS 17.1?

^{cf. "root on 17.1?" r/LineageOS}

Answer 1

It seems to be a Magisk 22.0 bug (issue #3949).

Rebooting into download mode (Home + Volume Down + Power) and running

heimdall flash --RECOVERY Magisk-v21.4.zip

rooted it!