This approach won't fix all of your issues. It mainly works for ones caused by the Joomla core.

These types of issues often show up after you run a Joomla core update.

If for some reason, for example, server resource exhaustion or a bug, only some files get updated, you may often see fatal errors or strange usability issues.

For example, you may see that your admin drop-down menus stop working.

Or you may find out, that you are not able to create new items.

The same upgrade, however, may work just fine on another site. In such scenarios, please try the following four steps.