If you attempt to restore from a custom firmware in DFU mode and the device was not pwned, you may run into the error. You may also run into this error when restoring from a corrupted firmware file.
You will need to use one of the following tools to enter a pwned DFU-mode. Please note that pwned DFU-mode is different from DFU mode, there are additional patches being uploaded to the iOS device to allow custom firmware restore.
The tools are:
- iReb (for version 3.1.2 and below)
- Pwnage Tool
- Turn off tinyUmbrella during restore, experiments show that it may cause problems.
- The phone must be powered off when start running the tool. If the phone is already in DFU mode when running the tools above, it may not work either.