Thank you Kovah. I will try it at the Weekend and report you any issue or bug, if i find one.
First: The Folder ‘/uploads/customer_files’ doesn’t exist. It is marked as an error by the upgrade process. I created it.
Second: After upgrading vom lastest to newest version, i get this error: "Unable to load the requested language file: language/German/custom_lang.php"
It is an empty file in the other languages folder, so i took the one from lang/english.
Third: Under “Aktualisierungen” the link from the 1.4 Update links to the 1.3.2 Announement. (Just ja small thing)