I was trying to use this to upgrade to 2.9.1. The upgrade kept failing with the following message.
Could not create directory: /httpdocs/wp-content/upgrade
Some research indicated this was a permission problem. I created the folder manually but still had problems. I ran the following in SSH session.
[root@host yaddayaddacom]# chmod -R 777 httpdocs
Then I was able to run the one click update. Be sure to turn permission back to something less open.