Updating joomla 1 5
So, what patch should I choose, and where can I find it?Your assumption that updating to the currect 1.5 realease will be 'good for security' is flawed. J1.5 has no support because it has come to the end of it's life, it is not because it is now secure and doesn't need patches.The current Long Term Release (LTR) is Joomla 2.5, the lastest Short Term Release (STR) is Joomla 3.0.Both of these are not directly upgradeable from any 1.5 version.In your case, since you currently have 1.5.20 and 1.5.26 is the latest 1.5.x version released, the latter would be the correct choice.
In case your Joomla 1.6 is an older version just keep reading. 1.6.0, 1.6.2, etc.), you have to upgrade it to 1.6.5 first. Fortunately, the upgrade process between the different 1.6 versions doesn't involve any database changes, so you only have to update the files.
As far as I can see, there are no update patches available to bring this up to date.
I'm aware that I can't update this to a 2.x or a 3.x version, but if I at least could bring this up to the newest version of the 1.5.x releases, that'd be good for security.
You also have to delete some files and directories, and you have to update the database used by the application by executing some SQL queries.
You can see the list of the files and directories that you have to remove from your Joomla installation in a file called