Where to find bootstrap logs

Hello, I seem to be blind or have lost my patience. When entering "host" (tried IP/hostname), "user"/"password", "activation key" and "Disable SSH.." under "Systems --> Bootstrapping" a blue info message appears "Your system is bootstrapping: waiting for a response..". After some long time, the bar changes to the red error bar saying: "Server error, please check log files.". Where are the logs for the bootstrap attempts? I claim, I searched "everywhere". Thank you and best wishes, Stefan