azure appservice shows only 502.5 HTTP Error with botframework v4.0

I have published the default echobot from the Microsoft BotFramework Template v4.0 to test the environment. After publishing the bot and connecting to the site it shows a 502.5 Error. In the eventlog the following error ist reported:

Application 'MACHINE/WEBROOT/APPHOST/BLABLABLA' with physical root 'D:\home\site\wwwroot\' failed to start process with commandline 'dotnet .\Bot Builder Echo Bot V4.dll', ErrorCode = '0x80004005 : 1.

The bot is registred and I have added the APP ID and Password to the .bot file.

I have also ran the command manually in the console. But there is no reaction ...

Edit: The bot is created with the Basic Bot template in Visual Studio and runs in the bot emulator without a problem.