Mail message import failed... a recurring problem?

Hi,

I cannot get my Apple Mail to work after a hard drive replacement. It says, "... Mail needs to import your messages ..." When I click Continue I get an error: message import failed: "Make sure you have available space in your home folder and try again."

(a) I do have available space, no worries there.

(b) I have followed other possible fixes with no luck. I have repaired permissions. I have found the V8 folder in Library/Mail/ and then I made sure I had permissions granted to me, the Mac owner. This seemed to work for others but had not worked for me.

(c) I followed the solutions presented here and had no luck: https://discussions.apple.com/thread/250050619?login=true

Any other possible solutions? Thanks, everyone.

Paul J