WARNING!!! ALL YOUR PRIVATE MODE DATA WILL BE LOST!!!
Well... sometimes when you restore a TWRP Backup... (Custom ROM)
and try to enable/activate Private Mode... You get this error... "Failed to enable Private Mode"
Your only option at this point is probably a full clean ROM Installation... (or wipe entire data/cache) and start all over again...
So... instead of starting all over again (or throwing your phone)
You can do this:
BEFORE YOU CONTINUE!!! ALL YOUR PRIVATE MODE DATA WILL BE LOST!!!
USE THIS METHOD IF YOU WANT TO AVOID A CLEAN INSTALLATION...
1. Navigate to /data/system/ and search for:
...and delete them all... (you might not have all 3 files, that's ok)
2. Navigate to /data/system/users/ and search for:
3. Reboot... & Done.... Private Mode is now fully operational.
Stock Rooted ROM? -> As a bonus... (Marshmallow) if you are using a Stock Rooted ROM and your Private Mode is not working... Flash this FILE