Many users on wordpress.com forums, complain lately about not being able to upgrade their wordpress installation from the wp-admin. Message being:

“The update could not be unpacked. Installation failed”

Now, if we look into the ftp server log we can notice that everything seems to be just fine. No errors or weird message spit out into the log file. But in fact, a bug affecting vsftpd was causing this behavior. In order to fix this issue and resume normal clean wordpress upgrade we will need to update to 3.0.3x from Debian unstable branch.