Yesterday, I was unable to auto upgrade my WordPress blog to current latest version 2.8.5. When click to use the “auto upgrade” feature showing on the top of my WordPress admin area, I get the following message:

Downloading update from http://wordpress.org/wordpress-2.8.5.zip.

My browser just showing “Done” and stopped there.

Obviously, the upgrade did not start at all.

The upgrade failed probably due to insufficient amount of memory a PHP script may consume.

TIPS: Try to de-activate all your WordPress plugins before doing the upgrade.
To do so, go to your Plugins >> Installed to de-activate some of the plugins you are using.
Then, re-try the “auto upgrade” button.

I applied this method, the upgrade did complete successfully!

Downloading update from http://wordpress.org/wordpress-2.8.5.zip.
Unpacking the update.
Verifying the unpacked files
Installing the latest version
Upgrading database
WordPress upgraded successfully

screenshot of wordpress blog upgraded successfully

Finally, I re-activated my WordPress plugins again.
Note: Make a backup first before you do any upgrade.