Infrastructure

You should be able to login using one of the URLs that are still
pointing to the old version, e.g. https://de.libreoffice.org/admin

If you want to display the content of a single page in your webbrowser
only and know the old URL, use the ?SubsiteID=8 parameter with an
"old-version-domain" (but with the URL-part from french project), for
example

http://de.libreoffice.org/participer/qui-est-qui/?SubsiteID=8

(if you want to browse the site this way, you should use a
browser-extension that adds this parameter to all pages, otherwise you
would have to manually add it each time you browse to another page)

Thank you Christian. I succeed to access the old website using the following url : http://de.libreoffice.org/home/lisez-moi/?SubsiteID=8#Linux

Best regards. JBF