Recently we have been upgrading and migrating lots of Joomla 3 websites over to Joomla 4 and from time to time, the Joomla Update screen does not show the Joomla 4 upgrade information. In most cases, this is because the Joomla 3 Update Channel is set to the Default Channel. To check and change this, while you are on the Joomla Update screen, press the Options button in the top right hand corner and see what Update Channel you are on. To see Joomla 4, this needs to be set to the Joomla Next Update Channel. 

However, in some instances we have found that even with that setting correct - the Joomla 4 update does now show. 

The recent release of Joomla 3.9.16 includes the addition of a database index to the users table. If your Joomla website happens to have duplicate usernames, this index addition will fail and you will see an error as in the attached image. The rest of the update will typically succeed just fine. 

Should you have this error, you must first find and solve the duplicate username problems. Each username in your site should be unique, so you should either rename or remove duplicates. 

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.

Joomla! is a fully-featured Content Management System that runs about 3% of the world's top one million websites. Like any software, updates are released from time to time to help keep it secure, squash some bugs; and advance the feature set. In this article, we show you what steps to take when Joomla updates are pending, before and after you apply those updates.

Disclaimer - This advice will be all you need for most sites, but do feel free to contact us if you need specialist Joomla update help.