Support

That's a bug (or at the very least a substandard feature) in Joomla itself. Joomla records two things when it installs a component, a record in the #__extensions table and a record in the #__schemas table. When you uninstall the component these records are supposed to be deleted automatically by Joomla's extension uninstallation code.

When this doesn't happen, you end up with a situation where Joomla cannot do a clean uninstallation. If the #__extensions record is present Joomla assumes it is doing an update instead of a clean installation even if the component's files and/or tables are no longer present on your site's disk and database respectively. If the #__schemas table record exists Joomla will apply the update SQL files provided with the component which have a version number higher than the recorded version_id on that table.

Either of them would result in a situation where Joomla tries to do an update instead of a clean install. However, since the extension is not fully installed (or at all installed!) this causes Joomla to throw errors and leave you with a half installed state you cannot recover from within its interface.

First, make sure that the Admin Tools package and component are removed from System, Extensions, Manage. If not, try removing them and reinstall Admin Tools.

If either reports an error or the installation fails you will have to do some database surgery.

Check the #__extensions table for any record where the name column is com_admintools. Note down the extension_id, e.g. 123

In the #__schemas table find the record that has the extension_id (e.g. 123) you obtained above. Delete it.

Now delete the #__extensions table record you found in the first step.

Delete all the database tables with _admintools_ in their name.

Delete the folders administrator/components/com_admintools, components/com_admintools and media/com_admintools if they are still present on your site.

Now you can do a clean installation of Admin Tools.

You're welcome!

To be fair, Joomla shouldn't let you end up in a situation where you have to perform database surgery to get unstuck. These issues are not hard to address, they are really hard to explain to the people who make the decisions and convince them they are bad enough to warrant a change in how Joomla works. We're getting there. I have started chipping away at the issues in Joomla Update and hopefully will manage to convince everyone involved that the extensions installation / update could also benefit from some much needed love :)