Hello Frank,
I hope you don't mind that I stick to English on this international platform. I see you had already asked the same as a reply to an older thread, so definitely good that you started it as a separate thread on its own.
Are you sure you are running Alfresco Community 3.6? The 3.x version only goes up to 3.4, after which 4.0 was the next major release. For 6.2.0, the only Community version available is 6.2.0-GA - I am not sure what your 6.2.0-3 is meant to refer to or whether that may just have been a typo.
In general, an upgrade over that many versions (assuming start is 3.4) can be quite a bit of work, as a straight upgrade is typically not possible over that many versions. Unfortunately, the public documentation has recently been reworked, and the documentation on 6.2 only deals with upgrades from 5.x versions and up - so I cannot reference a neat overview to showcase this.
For that reason it is a good idea to seek support from service integrators familiar with the version differences. If you are looking for community-oriented integrators from the German speaking area, there are ecm4u, contentreich and Acosix/myself, who are the more publicly visible / active in the community integrators. Though I can't speak for the others, I'd be open / available to discuss further details and see if some kind of support can be arranged (depending on timetables / other projects). Feel free to drop any of us a message via our official business contacts / homepages (e.g. info@acosix.de for myself).
