What I did so far:
1. I have uploaded all files according to the INSTALL-UPGRADE file
2. Directory permissions are set properly (777)
3. When I try to perform the upgrade according to the instructions in the INSTALL-UPGRADE file the regular installation routine pops up:
Your configuration has been verified.
XenForo is already installed in your database. Continuing will remove all XenForo-related data from your database!
Under no circumstances I don´t want XF have to remove all entries from the database - can I proceed here or is something going wrong here?
Any hints are appreciated.