I just had to do this. Don’t skip the release notes. They’re really good at highlighting potential pitfalls, just scroll back through and look for the heading “Breaking Changes.”

In my case there were a few, but they were only for API calls I’m not using, so I just did the update in one go and it worked out great. (Of course, I made sure to take a backup first.)

Oh! Also, try posting this here: https://practicalzfs.com/. That’s a discourse forum really focused on ZFS. Jim Salter runs it and Alan Jude often contributes advice. There are some folks there who know ZFS inside and out.

Checksum errors can often mean a failing component. It could be the other drive or maybe a sata cable. Is the original pool mounting correctly? If so, you should be able to do a simple rsync to move it to the new pool.