Feedback for v2.7

It’s not possible to install v2.7 on my device Google Pixel 8 Pro - recovery: error 21.

  • Vendor Name: Google
  • Device name: Pixel 8 Pro
  • Device CodeName: husky
  • Version of /e/OS: 2.7 u

Android 14 was installed on the phone when it was new. I had to update it to Android 15 to be able to activate the Enable OEM unlock in the Developer options.
After than I followed the Intall-Guide in Install /e/OS on a Google Pixel 8 Pro - “husky” and everything worked quite well so far…
After I had unlocked the bootloader and flashed the additional partitions, the next hurdle for me was to switch to recovery mode. After

entering fastboot --set-active=a

I switched to boot__a and then I also entered recovery mode.
I carried out the factory reset together with the format data.
When executing adb sideload <downloaded_file_name>.zip, the program aborted at 47% with the following error message:

Error:  recovery : Signature verification failed
Error:  recovery : error: 21
Install from ADB completed with status 2.
Installation aborted

I wonder if I’ve done something wrong.
Has anyone had similar experiences?
What can I do now?