It usually takes place if your machine failed to copy-paste or transfer files to or from that drive.
Maybe the port youre currently using is faulty or fails to provide enough power to your HDD.
Simply plug all of them out.
If youre using a laptop, disconnect absolutely all your peripherals, and keep only the external HDD connected.
you’re free to use your trackpad to control your unit.
see if the error is gone.
verify if the problem persists.
Replace your external HDD
Maybe your external HDD is the culprit.
If the HDD is wearing out, errors and glitches will become the norm.
Test if error 0X800701B1 still occurs if youre using a different HDD.
