These errors indicate that your computer's USB system can't properly communicate with the iPhone. The device is detected, but data transfer fails during the restore process.
Error 1601
USB communication failed entirely. iTunes sees the device but can't send data to it. Usually a driver problem or a bad USB port. Fix: Restart computer → try a different USB port → reinstall Apple Mobile Device drivers.
Error 1602
The Apple Mobile Device service isn't functioning correctly, or system files are corrupted. Fix: Restart computer → completely uninstall and reinstall iTunes → try on a different computer.
Error 1611
iTunes tried to put the device into Recovery Mode, but the iPhone bounced back out. The mode switch failed. Fix: Enter DFU mode manually instead of Recovery Mode → use a different USB port and cable.
Error 2001–2011
A range of USB chipset and driver errors, mostly seen on Mac. The computer's USB controller is having trouble maintaining a stable connection. Fix: Remove all USB hubs — plug directly into the computer → try every available USB port → restart → update macOS.
General USB troubleshooting checklist
Use an Apple-certified cable (not a cheap knockoff)
Plug directly into the computer — no hubs, monitors, or keyboards
Try every USB port on the computer
Restart both the computer and iPhone
On Windows: reinstall Apple Mobile Device USB Driver
On Mac: update macOS to the latest version
Try on a completely different computer
If you've tried everything above and the error keeps coming back, the problem is most likely physical — something broken inside the device that software can't fix. That's when it needs professional hands-on inspection.