Close iTunes completely and disable antivirus/VPNs that might block 3uTools from communicating with Apple's verification servers. Advanced Troubleshooting
In 3uTools’ options:
(such as a degraded NAND) that requires professional microsoldering.
Once 3uTools detects "DFU Mode" (instead of Recovery Mode), attempt the flash again. DFU mode is a deeper restore state that can bypass many software-level errors.
Reproduce and record context
Select at the bottom options panel. (Note: This will erase device data, but it is necessary to reformat a broken APFS partition).
Plug the cable directly into the motherboard (the ports on the back of a desktop) rather than a USB hub or front-panel port.
Before attempting complex software manipulations, rule out the most common hardware physical failure points.
: Corrupted Windows USB drivers or old 3uTools software configurations fail to push the initial payload.
: During standard restores, iOS checks if the battery can handle the intense voltage spike required for flash writing. Suboptimal or degraded batteries fail this check, prompting Error -75.
Below is a complete, step-by-step guide to troubleshooting and fixing 3uTools error -75 so you can successfully restore your iDevice. Understanding 3uTools Error -75
Expand the or Portable Devices tabs.