Is this still reproducible. I followed the instructions (except for changing alpha4 to alpha14) but I didnt get anything like your results

I can reproduce with the instructions provided using alpha4-dev. Install the French language pack and check again under 3rd Party Extensions Pre-Update Check .

closed for Reasons stated above. Please reopen if needed.

Set to "open" on behalf of @Quy by The JTracker Application at issues.joomla.org/joomla-cms/23063

Should be opened since it is reproducible.

too early on my side, apologize.

I can reproduce with the instructions provided using alpha4-dev

But can you reproduce with the current j4?

But can you reproduce with the current j4?

Yes.

Due to warning: PHP Warning: Creating default object from empty value in /libraries/src/Updater/Update.php on line 299

• Install a language pack, e.g. de-DE_joomla_lang_full_4.0.0v1-alpha1.zip from https://github.com/joomlagerman/joomla/releases/tag/4.0.0v1-alpha1

• Go to administrator/index.php?option=com_joomlaupdate

• Click on Check for Update

• Check error-log file

The question is now:
See lines here: https://github.com/joomla/joomla-cms/blob/4.0.0-alpha9/libraries/src/Updater/Update.php#L294-L309

• Why is $this->currentUpdate empty?
• Is it OK that it's empty but we should check that via if (!isset($this->currentUpdate)) before going on?

// For everything else there's...the default!
default:
	$name = strtolower($name);

	if (!isset($this->currentUpdate))
	{
		$this->currentUpdate = new \stdClass;
	}

	if (!isset($this->currentUpdate->$name))
	{
		$this->currentUpdate->$name = new \stdClass;
	}

• Or is something wrong with the language packages?

Looks like there were some changes recently.
Without modifying the version. I still get the error
PHP Warning: Creating default object from empty value in /Applications/MAMP/htdocs/joomla40/libraries/src/Updater/Update.php on line 299
Looks like the empty value comes from the language packs (which are 3.x packs) as I have 3 packs.
but no more Unknown Error in the Compatible column.

After modifying the version to
const EXTRA_VERSION = 'alpha9-dev';
same result.

I've made some additions to testing instructions in #23063 (comment)

if i try to install from url that language pkg i got

Did you use de-DE_joomla_lang_full_4.0.0v1-alpha1.zip (451 kB)?

There's also a FULL-Joomla package (18.1 MB). Maybe you took that?

yes you are right sorry
but if i try to install https://github.com/joomlagerman/joomla/releases/download/4.0.0v1-alpha1/de-DE_joomla_lang_full_4.0.0v1-alpha1.zip
got this

I use the current nightly. Wednesday, 26 June 2019 02:01:00 UTC and have no installation issues with that de-de package.

But I think there's a typo in plugin finder.php
impode( instead of implode(

Plugin "Extension - Finder" is not activated in my Joomla.

I'll make a pr for zhe impode thing

I'll make a pr for zhe impode thing

See: #25339

not sure it is the right way.....
give it a chance #25352

Closed as having Pull Request #25352