Maybe it’s me, but I wouldn’t call this issue resolved. Something is happening during the update process that really borks things up.
I had the same issue, where, for some reason, my normal username/password for mysql didn’t work, i.e. when I hit the upgrade.php page, I got a slew of error messages stating that I couldn’t connect. So, I switched the login to the root login and the update worked. Strangely, I could log into mysql via the command line using the “bad” account without any problems.
Also, there isn’t one definitive FIX for this issue. I used ghacks fix, switching the wp_capabilities value to {a:1:{s:13:”administrator”;b:1;}. There are a few misleading posts here as well. Do I need to make the changes to .htaccess? Who knows. No one has said if that’s necessary. And is the large entry mentioned by brunovernay for wp_capabilities necessary? Using only “{a:1:{s:13:”administrator”;b:1;}”, I’m not seeing any further problems.
And finally, artisan949 mentions using this in the wp_options table, which has to be wrong as the field names do not match.
