asoscott

Solution: switch from Pure-FTPd to ProFTPd as the FTP service. Obviously you need access to the server to do this, or contact tech support for your host.

I work for a great webhosting company (http://www.asmallorange.com) that has a lot of customers using WordPress. Lately we’ve been seeing this issue a lot more and it was driving me nuts.

This same problem happened about a year or so ago, and this bug report was made and a patched file was released to fix it:
http://core.trac.wordpress.org/ticket/10831

However, the modified class-ftp-sockets.php file did not work in this latest round of problems.

From what I’m able to tell by looking at the logs during an upgrade or plugin installation, the script attempts to write to an invalid path (usually /public_html/somefile rather than /home/username/public_html/somefile) before using the correct path. It does this for each and every file, so during a major operation like an upgrade where a lot of files are involved it takes a very long time. Eventually the script freaks out and tries to access more memory than is allowed by our suhosin php security module. In most cases it attempts to access 256MB while our default limit is 32M. Suhosin blocks the script and the installation fails.

While working on the dedicated server of a customer that was having this problem, I changed the FTP configuration to use ProFTPd in place of PureFTPd, and the upgrade worked immediately and without complication.

Hopefully this will help someone, and hopefully WP can fix this bug!