cannot install new language in J4

[Kompas]

Hello support,

Whether going to system page and choosing Install Languages or going to Manage Languages or Content languages on the admin system page, and then choose the option « Install Languages », the result is the same as seen in picture: install languages J4(1). I then click on rebuild your update server table, select all by ticking the box left of Status, then click the button Rebuild. A green message comes up stating Update sites have been rebuilt from manifest files, see picture: install Languages J4(2), but if I then go back to system -> install a new language, the same orange error message is shown. So I can’t install new languages via the admin system page (haven't tried yet to download a language pack and install from there on. Am I forgetting something?
Thanks in advance,
Kompas

[Kompas]

TIME_OUT -> J4 site has crashed now, I will have to restore a version from 3 days ago. Gone is the weekend work. Site crashed while I was looking into the install languages issue.

[Kompas]

Hello again. The site is alive again thanks to the suggestions of Nicholas, but luckily I made notes of the work done over the weekend. But the issue remains the same: I cannot install languages from the backend, the list of languages doesn't even show up, so my original description of the error is still valid. There are no other messages besides the ones that can be seen in the pictures, attached to the first message.
Have a nice day,
Kompas

[toivo]

Language packages are like extensions. Download the language you want from Joomla 4.x Translations: Download the language packages for your website, go to System - Install - Extensions and install the language pack.

[Kompas]

Hi toivo, thanks for your response. I'm sure one can install languages that way, but the issue was that installing language packages via the backend of J4 is not possible. Maybe next J4 update will fix his.
Have a nice day,
Kompas

[toivo]

Hi toivo, thanks for your response. I'm sure one can install languages that way

Did you try to install a language pack as an extension to Joomla 4.2.9, as described? It works.

If you did try the extension install method, what was the error message? Please copy and paste the message into your reply or take a screenshot and attach the file.

The list of languages in the back end is of course an issue, but the above installation method is a workaround.