What you'll need:
1. The phone must be rooted
2. Install ROM toolbox lite on the phone
3. A PC
4. Download and Install HxD Hexeditor on the PC
Follow the steps below.
1. Switch on the WiFi on your phone.
2. Go to settings > about and write out your phone's Wi-Fi MAC Address displayed there. It should look like xx:xx:xx:xx:xx:xx
3. Switch off the WiFi on your phone
4. Launch ROM toolbox lite on your phone and select root browser
5. Navigate to File system root/data/nvram/APCFG/APRDEB and copy the file named 'WIFI' from there to the SD Card of your phone
6. Send the WIFI file to the desktop on your PC
7. Launch HxD-Hexeditor on your PC and click on OPEN or Ctrl+O then select the WIFI file you just sent from your phone
8. Go to the first row in the opened WIFI file then go to column no. 04
9. Insert the value of your actual MAC Address (the one you copied @ step 2) two by two from column 04 to 09 (Ensure that none of the value is ZERO) example: if your MAC address is 00:08:62:92:ee:fa then you'll fill it as:
04 05 06 07 08 09
00 08 62 92 ee fa
10. SAVE this change
11. Close Hexeditor and copy the newly edited WIFI file from your PC to the SD card of your phone (ensure to delete the older WIFI file from SD Card before copying this file).
12. Launch root browser in ROM toolbox lite on your phone and move this file from SD card root to File system root/data/nvram/APCFG/APRDEB
13. Long press the WIFI file then set permission to rwrw (tick first two boxes on row 1 and 2)
13. Turn on your wifi then turn it off again
Your phone's WiFi NVRAM Error should have been resolved. If this issue persists, simply copy the WIFI file from a friend's phone of the same type then repeat the above steps.
Source: How to fix WiFi NVRAM WARNING: ERR 0x10