I was running Magisk on Android 11 on my Google Pixel 5. I installed it using a patched boot image from 11.0.0 (RD1A.200810.021.A1, Oct 2020, EU carriers). Today Android 11 prompted me with an update, I installed it without thinking about the consequences. After rebooting Magisk stopped functioning. So I rebooted to fastboot mode and flashed the same patched boot image as i did the first time. I flashed both boot_a and boot_b, I remembered i did that the last time.
After that the phone is stuck in a boot loop.
I also tried flashing the unpatched boot image from the original image, but same effect. Maybe i had to patch the latest magisk version on a fresh boot image, but can't do that anymore without access to magisk on my phone. Was running the latest canary YAHFA version.
Don't know what to do anymore, really hoping there is a solution without loosing all my data.
In the end i fixed it with extracting the boot image from the correct factory image. At first I didn't see that the latest image was at the end of the list here https://developers.google.com/android/images Flashing the boot image gave me a 'no command' screen. But I was able to boot into safe mode. After that i could patch the boot image file with magisk, and patch it in fastboot. And then everything was working again!