The “Bad timestamp” error is one of the 422 (Unprocessable Entity) errors that indicates while creating a session an invalid timestamp value (which is based on the device time) is sent.
When the SDK creates a session token it passes a timestamp param to the server.
Please, try synchronizing the time on your devices with NTP service or just tick 2 checkboxes in the devices' settings: Automatic date & time, and Automatic time zone.
Please note that our Cloud server uses UTC time.
The difference in time on your devices and your local time (time provided by NTP) should not be more than one hour. Otherwise, you will be receiving errors like that ("Bad timestamp").
Feel free to check our official documentation for more information that will help you to integrate QuickBlox services into your applications / projects or contact our Support team by submitting a ticket if you have any other questions.