For my part, I added ".svn" to my URL and it worked: https://xx.yyy.zz -> https://xx.yyy.zz.svn

Some SVN servers configured with Apache + mod_dav_svn use the .svn extension in the URL to point to the actual repository on the server.

If you forget .svn, Apache can't find the repository → Could not find the requested SVN filesystem. Probably the result of the Apache version upgrade!