Hey,
I had this problem too, pass many hours to discovery what is....
First the problem is when i try to unlock Nokia 1110i ( DCT4+ ) patching MCU file in older version of MXKEY (3.3. rev1.8), and allways get error at the end...Something with roolback operation...
So, with this new update of MXKEY (3.4) i try to unlock but always this "Error 01".
The solution pass to patching MCU again but using JAF Emulator, with my UFS Box
And voilá, phone unlock!
Try this and tell us the result.
BR