Mr Papa said
Odd. In your case, what method does the wp updater use (ie ssh, ftp, direct, etc). This is all wp code.
Can you look in your wp uploads dir for current year/month and see if you have an admin-bar.zip file in there?
What browser? Have you tried another?
What is your php upload limit?
I’ve got exactly the same error on my first update attempt.
I am using SSH2 via SSH/FTP update support plugin as my ftp is generally disabled for security reasons. There is no admin-bar.zip in my uploads/year/months.
I am running FF 18 – but the same on Chrome and Opera.
My upload limit is 256M.
I guess, it is the SSH which causes trouble here.
Going to do manual upgrade instead.
Edit: Tried updating themes and plugins the wp updater way but to no avail. They do not exactly fail – they just start and immediately finalize with nothing updated – no message, no input request (i.e. SSH2 password/key file). And strange – updates in WP itself run without any hazzles. Will have to do it manually, as well.