Problems importing v8 T3D into v11 - Section not found

Hello all,

i got the task to setup a new TYPO3 v11 Installation and to import the Page tree from the old v8 Installation.

The Import itself is working (except for the cms-impexp commandline) but after the import the pages are not editable as they show a 503 error and the Message Section Configuration not found.

Does anybody have a clue on what is going wrong here and what i can do to access the page content?
Thank you in Advance.

You still got some more information here: TYPO3: Problems importing v8 T3D into v11 - Section not found - Stack Overflow