Automatic WordPress upgrade problem

I’ve just spent 5 hours trying to get WordPress automatic upgrade to work. Each time I get the message:

“Unable to locate WordPress Root directory. Installation Failed”

If you search for this problem, you see that there are HEAPS of users with the same problem, and there’s no shortage of remedies, from adding code to wp-config.php to using wordpress admin username instead of the FTP username.

None of this works for me. Upgrading plugins is never a problem, so why is upgrading WordPress so impossible?

I still don’t know how to get automatic WordPress upgrade to work, and I think it’s about time to fix this problem in future WordPress updates, hopefully in 3.0.2.