Hello Yusuf Oezeren
Welcome to Microsoft Q&A Platform, thanks for posting your query here.
The error message "ERR_BAD_RESPONSE" indicates that the Serial Console feature is not able to establish a connection with the VM.
Please try these troubleshooting steps to see if it helps resolve the issue:
-Check the configuration of the VM and make sure that the Serial Console feature is enabled.
-Try to restart the VM and see if that helps.
-Try to stop and start the VM, once the VM is started this will be moved to new host.
Hope this helps.