JER3 404 Handler, provides an automated way to recover from NOT-SO-TRUE 404 errors and to customize the handle of actual 404s.
Keep in mind that Joomla SEF URLs may change, among others, by a modification in the menu structure or by the change in some menu item alias. However the internal URL (non-SEF) remains unchanged.
As a prevention step, the plugin stores in a database table, the SEF URL and its associated non-SEF URL of any valid page accessed in your Joomla website.
As a first corrective step, if for any reason, the SEF URL gets changed, the former SEF URL will trigger a 404 error. The JER3 404 Handler plugin, will automatically detect 404 errors and will search in its database table if there is an associated non-SEF URL for the one that triggered the 404 error. If so, the plugin will get build the new SEF URL for such resource and smoothly redirects the visitor to the new URL.
In case the first step fails, as optional second step the JER3 404 Handler plugin could try to build a keyword list from the requested SEF URL and redirect the visitor to the Joomla search component, looking for any content related to such keywords.
Finally, when the two steps above fail, the plugin empowers you to decide how the 404 error should be handled: trigger the default Joomla error page, let the Joomla redirect component to try to solve the error, redirect to the homepage or redirect to elsewhere.