Thank you all for your feedback and discussion. Based on your views and the user reports we have received regarding Hasleo Backup Suite and Hasleo WinToUSB, I would like to provide the following summary and response.
@al3x, you mentioned that "creating and deleting a small text file every minute or so might solve the problem."
- That is a clever idea. However, according to the user feedback we have received, the 0x1B1 error usually occurs during continuous reading or writing operations. This means that even during the transfer of large files, the connection can suddenly drop. Therefore, periodically creating and deleting small files is unlikely to effectively prevent disconnections that happen during intensive I/O operations.
@Froggie, your analysis of the root causes is very accurate, and I fully agree with the following points:
- About the device automatically going offline: You are right that ordinary USB drives do not "actively" set themselves to an offline state. However, some drives do have built-in thermal protection that may reduce write speeds or even temporarily stall when the drive overheats after extensive writing – but they do not actively set themselves offline.
- About the root cause: The power supply issues, unstable cables, and low-quality enclosures you emphasised are indeed the most common causes of this problem. As you pointed out, if the USB device is not self‑powered (i.e., lacks a separate power connection), it draws power from the USB port. During heavy read/write operations, significant power fluctuations can occur, which easily lead to unstable connections and trigger the "A device which does not exist was specified." error.
Based on the above discussion and the cases we have seen in the forums, we can provide the following systematic troubleshooting advice to users who encounter this issue:
- Check physical connections – This is the first and most important step. Try changing the USB port (preferably using ports on the back of the motherboard), the cable, or using an enclosure with an independent power supply.
- Check power management settings – In Windows Device Manager, locate all "USB Root Hub" entries under "Universal Serial Bus controllers", go to their "Properties" => "Power Management" tab, and uncheck "Allow the computer to turn off this device to save power".
Regarding solving this issue, our idea is that after detecting that the drive has gone offline, the program should attempt to re‑open the drive and then continue with the remaining backup or restore operations. This should be technically feasible. However, the concern is that when the drive suddenly goes offline, data that has already been written may not have been fully flushed to the backup image file or the target drive. This could result in a corrupted backup image file or corrupted restored data – which is our main worry.
Thank you again for your valuable input!
