Troubleshooting a Joomla Update problem
A few things can go wrong when updating Joomla though later releases tend to have fewer and fewer issues. We describe some common issues and provide solutions here as well as examining tools to diagnose the root causes.
1. One-click didn't work. The one-click update basically grabs the update files from the Joomla code repository and installs them similar to the way extensions get installed. If you're behind a firewall or on a weak connection this can fail. In this case, you have the option of downloading the upgrade package ZIP file manually and installing it via the Joomla update extension. If that fails there is a third option where you extract the contents of the upgrade package and overwrite the files on your Joomla installation. If you use that method you'll also need to follow our next troubleshooting tip to apply the database update.