Nothing says that there must be at least one category.

Actually, that specific error at that specific line means that nobody is doing error checking in the getTransitions method, a common missing thing in Joomla's code. The getItems doc block clearly indicates a boolean false is returned on failure.

As you can create a category on the fly within the article edit form there shouldnt be a reason that you cannot delete all empty categories

@brianteeman you are right.
@mbabker After a new installation this error has diappeared. Sorry for wrong alert.

There's still a bug to be addressed and something should be open (either this with the title corrected or a new item) to address it. This line does not check for a boolean false return, meaning there is no error handling and that should be fixed to prevent the fatal error you posted in your original post.

@chmst can you please open an Issue as @mbabker suggested above?

unable to replicate with

• Install a fresh latest staging without data
• go to com_content, categories
• trash and delete the category

both
..index.php?option=com_content

and
...index.php?option=com_categories&extension=com_content

gives expected result
No Matching Results

what i'm missing ?

The title is not relevant at this point. As I noted in #24452 (comment) the bug is the lack of error checking when calling $this->getItems(), if for some reason that returns a boolean false that scenario is not accounted for which results in the "Argument 1 passed to Joomla\Utilities\ArrayHelper::getColumn() must be of the type array, boolean given, called in administrator\components\com_content\Model\ArticlesModel.php on line 516" fatal error from the original issue post. You're not going to replicate this issue without breaking something else.

As I said, the error has diappeard after a new installation. Probably it was a database update between the last pulls which caused the error.

did you mean after

something like

if (!$items)
{
	return false;
}

?

Right.

Set to "closed" on behalf of @franz-wohlkoenig by The JTracker Application at issues.joomla.org/joomla-cms/24452

closed as having Pull Request #24458