Updater doesn't find update packages

I'm pretty new with owncloud and am currently using my first installation - on Debian.
I wanted to update my instalation to the current verion 9.0.4, but am stuck:
1. If I click on the "Update Center button" under Updater in the Admin section absolutlely nothing happens.
2. trying to start the update manually "php application.php upgrade:start"
results in this:
Checking system health.
- file permissions are ok.
Current version is
Can't fetch feed.
cURL error 6: Could not resolve host: updates.owncloud.com
I tried to brwose to http://updates.owncloud.com and this returns a message "Page has moved". Obviously the error message makes sense.
How can I fix this, i.e. where are the updates now and how can I tell the script to use a differnt path.
Thanks for pointing me into the right direction.

Could not resolve host: updates.owncloud.com

You can get the current archives from: https://owncloud.org/changelog/#latest9.0

For the URL error, you can create an issue on the bugtracker.

Personally, I do not rely on the updater app, there are too many reported problems and the manual upgrade isn't so difficult either.

Thanks a lot for your reply and pointing mme to the update packages. I will dig into the details for a manual update then (I was hoping to avoid this, since I'm not very expierenced with Linux systems).