Thank you, it has worked !
My device was an MT6580 (Vonino Xylo X), running Marshmallow! It will also FIX error 0x02!!
I searched a lot for this WIFI file, most fixes contain an old WIFI file that does not work, but this one does !!!
Some more instructions for the one that it did not work (you need ROOT, instructions are for Ubuntu):
adb push WIFI /data/
cp /data/WIFI /nvdata/APCFG/APRDEB/
chmod 0660 WIFI
Anyway, you can find many tutorials online on how to copy the WIFI file to the APRDEB (using Root Explorer etc), but this will work for Android 6.0!!! All others did not work for me, I got error 0x02 after flashing!