I created an Investigation -> Activities of failed web request (HTTP Status is >= 400) when accessing to a domain name. In the results, notice TLS web request with HTTP Status = '-'
404 error response when making a web request to '/...
Wie man einen 400 Bad Request Fehler behebt (Ursachen und Lösungen)
What is a Bad Request Error 400 and How Do You Fix It? - GreenGeeks