Failed WordPress Upgrade

The error message:

Fatal error: Call to undefined function update_core()

The Cause:

You don’t have enough disk space on your hosting account anymore.

The Fix:

Pick one:

  • Ask your web host to bump up your allowed disk space
  • Delete unneeded files on your account
  • Move to a new web host


I never ran into this problem before, but during an update to WordPress 3.4, the error kept appearing every time the upgrade script tried to unpack the downloaded zip file from  It would be helpful if they included a message about it to let you know you may be out of space, but at least you can Google the error and find this page now 🙂

About Will Chatham

Will Chatham is the Application Security Engineer at a cyber security research and development firm. Since Netscape 2.0, he has worked in a wide array of environments including non-profit, corporate, small business, and government. His varied background, from web developer to search engine optimizer to security professional, has helped him build a wide range of skills that help those with whom he works and teaches.
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