Hey guys,
I tried to join the ETS2 universe again.
I downloaded the new launcher (version 1.0.0.4) and changed my ETS version (version 1.26.x) as described.
If I try to start the launcher this error message appears.
I allready reinstalled the game and the launcher.
The installation paths are correct too.
I hope someone can help me.
-M1k3D3l7a
EDIT: I solved the problem. Admins, please close this question. Thank you