The device is not ready
The most probable cause is a possible hardware defect. Other causes could include loose connection, obsolete drivers, or compatibility issues between the external hard drive and the operating system. Before we proceed further, the question is – whether you were able to access the hard drive on your system even once before getting the error or not. If not, then please verify the compatibility of the device with your operating system. After that, you could proceed to the following solutions: 1] Check the hardware connections One of the reasons for this issue could be loose connections between the cable of the external hard drive and the USB port. Try reconnecting the device. If it doesn’t work, try connecting the device to a different USB port. 2] Run the Hardware and Devices & USB Troubleshooters The Hardware and Devices troubleshooter checks for issues with hardware connections and reports if any. It can also resolve minor problems. It is not a part of the Troubleshooting Settings page anymore, so you could access it via the Control Panel menu. You could also run the USB Troubleshooter. Restart the system one the process has completed. 3] Run the CHKDSK command The CHKDSK utility helps in identifying the bad sectors in a drive and fixing them. In the case we are discussing here, it could be possible that bad sectors in the external hard drive are the reason for the problem. You could run the CHKDSK utility for fixing it. Open an elevated Command Prompt and run the following command: 4] Update the drivers of the device While we could update the drivers of any device through the Device Manager, in this case, I would suggest downloading the latest set of drivers from the manufacturer’s website. Install them first and then correct the external hard drive. 5] Update the USB drivers Other than updating the drivers of the external hard drive, we could also try updating the USB drivers. Press Win + R to open the Run window. Type the command devmgmt.msc. Press Enter to open the Device Manager. Expand the list for Universal Serial Bus Controllers. Right-click and select Update driver for all the drivers in that list. Restart the system. If these solutions do not work, you might consider replacing the hard drive or consulting a hardware technician.