Check-out failed with the following error

When an article is checked out, you will see a lock icon next to the article and you can no longer edit it.

A lock on a Joomla article

When a file is edited in the administrator area of Joomla, the file is automatically locked as checked out with a padlock icon.

This means that the item can only be edited by the user who checked it out. It is not possible for multiple users to edit one item at the same time. This prevents data being lost when saving.

If an article remains locked while no one edits it, it must have been locked incorrectly (for example, by backspace instead of the "Save" button.

The error message: Check out failed

When you try to open the article you will see this message:

Check out failed due to the following error:The user checking out does not match the user who checked out the item.You do not have permission to use this link for direct access to this page.

Joomla item check-in

Using the Check-in button, you can unlock all checked-out items on your Joomla site so that they can be edited again.

Select the the item you want to check in and click the "Actions" button at the top and then "Check in".

Checking in all items

Using the General Check-in, you can unlock all checked-out items on your Joomla site so they can be re-edited.

Use the "General Check-in" button or the control panel or go to "System > General Check-in", select the Database table you want to check in and click the "Check-in" button at the top.

Checking in items automatically with the Scheduled Tasks plugin

As of Joomla 5, there is a task plugin that allows you to check in items at any time. To do this, go to system >> scheduled tasks and create a new task.

Choose the time interval and how long an item should be checked out. (This is at least 1 hour, because you don't want an item to be checked in when someone is still working on this item.)

Then you save the task and you're done.

For more information about task plugins, read the article "scheduled tasks" in the knowledge base.